Climate and average weather in Olney
In Olney, the summers are humid, hot, showery, and partly cloudy and the winters are cold, snowy, and partly cloudy.
Over the course of the year, the temperature in Olney typically varies from 28°F to 87°F, and is rarely below 14°F or above 95°F. July is the hottest month of the year, while January is the coldest.
Based on the travel score, the best times of year to visit Olney for warm-weather activities are from mid April to mid June and late August to late October.
- Hottest
- Jul
- 87°
- Coldest
- Jan
- 28°
- Wettest
- Sep
- 4.5 in
- Driest
- Feb
- 2.9 in
- Rain / yr
- 43.2 in
- 116 wet days
- Daylight
- 9.2–14.8 h
- shortest–longest
- Elevation
- 541 ft
- 39.2°N
- Clearest
- Oct
- 52% cloud
Olney is census-designated place and unincorporated area in Montgomery County, Maryland, United States, suburb of Washington, DC.
- Density
- 804/km²
- people per km²
- Founded
- 1832
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Olney weather by month, at a glance
The whole year in one picture — sky, rain, humidity, temperature and travel score. Click any band to jump to its full chart.
Each stripe is one measure across the whole year, stacked so a single day reads top to bottom. The sky band runs overcast grey on top down to clear blue at the base — more blue means sunnier — followed by the rainfall curve, the humidity band, a temperature strip that tints each stretch of the year by how warm its average high is, and the travel-score line at the foot. Scan straight down any date to read that day across every measure at once; the score climbs highest around mid April to mid June.
Temperature through the year
Daily average highs and lows in Olney, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
The hot season lasts 4.0 months, from May 24 to September 21, with daily high temperatures above 75°F. The hottest month of the year in Olney is July, with an average high of 87°F and low of 69°F.
The cool season lasts 3.1 months, from December 1 to March 5, with daily high temperatures below 50°F. The coldest month of the year in Olney is January, with an average low of 28°F and high of 41°F.
Days typically run about 16°F warmer than nights year-round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 41 | 44 | 53 | 65 | 73 | 82 | 87 | 84 | 78 | 66 | 55 | 45 |
| Avg low (°F) | 28 | 29 | 36 | 46 | 56 | 65 | 69 | 68 | 61 | 49 | 39 | 32 |
| Avg high (°F) | Avg low (°F) | |
|---|---|---|
| Jan | 41 | 28 |
| Feb | 44 | 29 |
| Mar | 53 | 36 |
| Apr | 65 | 46 |
| May | 73 | 56 |
| Jun | 82 | 65 |
| Jul | 87 | 69 |
| Aug | 84 | 68 |
| Sep | 78 | 61 |
| Oct | 66 | 49 |
| Nov | 55 | 39 |
| Dec | 45 | 32 |
How hot and cold Olney really feels
The felt-temperature range through the year — heat index on the day's high (summer humidity), wind chill on the night's low (winter wind). The dashed lines are the plain thermometer; the gap is how much hotter or colder it really feels.
On the coldest nights, wind chill pulls the feels-like down to about 18°F (around January 24), with roughly 123 freezing days a year (feels-like at or below 32°F), worst in January.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Feels-like high (°F) | 41 | 44 | 53 | 65 | 73 | 83 | 88 | 85 | 78 | 66 | 55 | 45 |
| Air high (°F) | 41 | 44 | 53 | 65 | 73 | 82 | 87 | 84 | 78 | 66 | 55 | 45 |
| Feels-like low (°F) | 20 | 21 | 30 | 43 | 56 | 65 | 70 | 68 | 61 | 47 | 34 | 25 |
| Air low (°F) | 28 | 29 | 36 | 46 | 56 | 65 | 69 | 68 | 61 | 49 | 39 | 32 |
| Feels-like high (°F) | Air high (°F) | Feels-like low (°F) | Air low (°F) | |
|---|---|---|---|---|
| Jan | 41 | 41 | 20 | 28 |
| Feb | 44 | 44 | 21 | 29 |
| Mar | 53 | 53 | 30 | 36 |
| Apr | 65 | 65 | 43 | 46 |
| May | 73 | 73 | 56 | 56 |
| Jun | 83 | 82 | 65 | 65 |
| Jul | 88 | 87 | 70 | 69 |
| Aug | 85 | 84 | 68 | 68 |
| Sep | 78 | 78 | 61 | 61 |
| Oct | 66 | 66 | 47 | 49 |
| Nov | 55 | 55 | 34 | 39 |
| Dec | 45 | 45 | 25 | 32 |
Average hourly temperature in Olney
A compact picture of the whole year, hour by hour: each column is a day, each row an hour, and the color is the modeled average temperature. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
Read left to right for the day of the year and top to bottom for the hour of the day; the color is the modeled temperature, cool blues through to hot reds on the same scale as the other charts. A vertical slice is a single day's swing — coolest just before dawn, warmest in the mid-afternoon — while a horizontal slice follows one hour across the seasons. The darker overlay marks night and the lighter one the twilight around sunrise and sunset. Colors run warmest on July afternoons, near 87°F, and coldest before dawn in January, near 28°F.
Olney weather by month
Every month at a glance. Click a month for its detailed page.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 41° / 28° | 3.1 | 8.4 | 3.1 | 9.6 | 0.1 |
| Feb | 44° / 29° | 2.9 | 8.4 | 3.2 | 10.5 | 0.9 |
| Mar | 53° / 36° | 3.9 | 10.2 | 2.3 | 11.7 | 3.0 |
| Apr | 65° / 46° | 3.4 | 10.2 | 0.2 | 13 | 5.7 |
| May | 73° / 56° | 3.8 | 11.3 | 0 | 14.1 | 6.5 |
| Jun | 82° / 65° | 3.7 | 11.2 | 0 | 14.7 | 5.7 |
| Jul | 87° / 69° | 4.1 | 11.6 | 0 | 14.5 | 4.7 |
| Aug | 84° / 68° | 3.6 | 10.5 | 0 | 13.5 | 5.4 |
| Sep | 78° / 61° | 4.5 | 9.6 | 0 | 12.3 | 6.9 |
| Oct | 66° / 49° | 3.5 | 7.8 | 0 | 11 | 6.4 |
| Nov | 55° / 39° | 3.0 | 7.6 | 0.3 | 9.9 | 3.7 |
| Dec | 45° / 32° | 3.6 | 8.9 | 1.9 | 9.3 | 1.1 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Olney gets about 43.2 in of precipitation a year. On a typical day the chance of rain is often wet, but that rises and falls sharply with the seasons.
The wetter season lasts 5.9 months, from around Feb 25 to Aug 24, peaking in June at about 40% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Nov 8.
September is the wettest month by volume, with 4.5 in over about 10 wet days; February is the driest, with 2.9 in. Some of the cold-season precipitation falls as snow.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 28 | 30 | 33 | 34 | 36 | 37 | 37 | 35 | 30 | 26 | 26 | 29 |
| Rain days | 8 | 8 | 10 | 10 | 11 | 11 | 12 | 11 | 10 | 8 | 8 | 9 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 28 | 8 |
| Feb | 30 | 8 |
| Mar | 33 | 10 |
| Apr | 34 | 10 |
| May | 36 | 11 |
| Jun | 37 | 11 |
| Jul | 37 | 12 |
| Aug | 35 | 11 |
| Sep | 30 | 10 |
| Oct | 26 | 8 |
| Nov | 26 | 8 |
| Dec | 29 | 9 |
Monthly rainfall
Over a full year, Olney collects about 43.2 in of rain across 116 wet days — roughly 3.6 in in an average month.
It doesn’t fall evenly. September is the wettest month with 4.5 in, while February is the driest at just 2.9 in. The three wettest months alone bring about 29% of the year’s total, and some of the cold-season precipitation falls as snow.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (in) | 3.1 | 2.9 | 3.9 | 3.4 | 3.8 | 3.7 | 4.1 | 3.6 | 4.5 | 3.5 | 3.0 | 3.6 |
| Rain days | 8 | 8 | 10 | 10 | 11 | 11 | 12 | 11 | 10 | 8 | 8 | 9 |
| Snow days | 3 | 3 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 |
| Rainfall (in) | Rain days | Snow days | |
|---|---|---|---|
| Jan | 3.1 | 8 | 3 |
| Feb | 2.9 | 8 | 3 |
| Mar | 3.9 | 10 | 2 |
| Apr | 3.4 | 10 | 0 |
| May | 3.8 | 11 | 0 |
| Jun | 3.7 | 11 | 0 |
| Jul | 4.1 | 12 | 0 |
| Aug | 3.6 | 11 | 0 |
| Sep | 4.5 | 10 | 0 |
| Oct | 3.5 | 8 | 0 |
| Nov | 3.0 | 8 | 0 |
| Dec | 3.6 | 9 | 2 |
Snow in Olney
Average snowy days through the year, the snow-season span, and estimated snowfall — for ski trips and the perennial 'will there be snow at Christmas?' question.
Olney averages about 11 snowy days a year. Snow season runs roughly Nov 26 to Apr 7 — about 4.4 months.
February is snowiest, with roughly 3 days of snow and an estimated 11 in of snowfall. Over the year that adds up to an estimated 31 in of snow.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Snow days | 3 | 3 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 |
| Snowfall (in) | 8 | 11 | 7 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 5 |
| Snow days | Snowfall (in) | |
|---|---|---|
| Jan | 3 | 8 |
| Feb | 3 | 11 |
| Mar | 2 | 7 |
| Apr | 0 | 0 |
| May | 0 | 0 |
| Jun | 0 | 0 |
| Jul | 0 | 0 |
| Aug | 0 | 0 |
| Sep | 0 | 0 |
| Oct | 0 | 0 |
| Nov | 0 | 1 |
| Dec | 2 | 5 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Olney, the average share of the sky covered by clouds shows moderate seasonal variation over the course of the year.
The clearer part of the year begins around June 27 and lasts for 5.1 months, ending around November 29. The clearest month is October, when the sky is clear, mostly clear, or partly cloudy 55% of the time on average.
The cloudier part of the year begins around January 3 and lasts for 5.7 months, ending around June 26. The cloudiest month is May, when it is overcast or mostly cloudy 57% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 47 | 46 | 44 | 43 | 43 | 45 | 50 | 52 | 51 | 55 | 51 | 47 |
| Cloudier (%) | 53 | 54 | 56 | 57 | 57 | 55 | 50 | 48 | 49 | 45 | 49 | 53 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 47 | 53 |
| Feb | 46 | 54 |
| Mar | 44 | 56 |
| Apr | 43 | 57 |
| May | 43 | 57 |
| Jun | 45 | 55 |
| Jul | 50 | 50 |
| Aug | 52 | 48 |
| Sep | 51 | 49 |
| Oct | 55 | 45 |
| Nov | 51 | 49 |
| Dec | 47 | 53 |
Daylight, sunrise and sunset
Hours of daylight through the year, with sunrise and sunset times.
The gold band is daylight — sunrise runs along its lower edge, sunset along the upper — so it widens toward summer and pinches toward winter, with night the dark area above and below. The longest day, around June 19, brings about 14 h 48 min of light; the shortest, around December 19, only 9 h 12 min — a swing of roughly 5 h 36 min.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 9.6 | 10.5 | 11.7 | 13.0 | 14.1 | 14.7 | 14.5 | 13.5 | 12.3 | 11.0 | 9.9 | 9.3 |
| Sunrise (AM) | 7:32 | 7:09 | 6:27 | 5:38 | 5:00 | 4:46 | 4:59 | 5:26 | 5:55 | 6:25 | 6:59 | 7:27 |
| Sunset (PM) | 5:04 | 5:37 | 6:08 | 6:39 | 7:09 | 7:31 | 7:29 | 6:59 | 6:10 | 5:22 | 4:48 | 4:42 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 9.6 | 7:32 | 5:04 |
| Feb | 10.5 | 7:09 | 5:37 |
| Mar | 11.7 | 6:27 | 6:08 |
| Apr | 13.0 | 5:38 | 6:39 |
| May | 14.1 | 5:00 | 7:09 |
| Jun | 14.7 | 4:46 | 7:31 |
| Jul | 14.5 | 4:59 | 7:29 |
| Aug | 13.5 | 5:26 | 6:59 |
| Sep | 12.3 | 5:55 | 6:10 |
| Oct | 11.0 | 6:25 | 5:22 |
| Nov | 9.9 | 6:59 | 4:48 |
| Dec | 9.3 | 7:27 | 4:42 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Olney averages about 9 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 7 and 13 days.
The sunnier stretch runs 3.4 months, from around Aug 23 to Dec 5. The sunniest month is October, with roughly 13 sunny days (mixed).
The greyest month is June, down near 8 sunny days — about 40% fewer than the October peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 9 | 8 | 9 | 8 | 8 | 7 | 8 | 9 | 11 | 13 | 11 | 10 |
| Sky | Mixed | Mixed | Mixed | Mixed | Gloomy | Gloomy | Gloomy | Mixed | Mixed | Mixed | Mixed | Mixed |
| Sunny days | Sky | |
|---|---|---|
| Jan | 9 | Mixed |
| Feb | 8 | Mixed |
| Mar | 9 | Mixed |
| Apr | 8 | Mixed |
| May | 8 | Gloomy |
| Jun | 7 | Gloomy |
| Jul | 8 | Gloomy |
| Aug | 9 | Mixed |
| Sep | 11 | Mixed |
| Oct | 13 | Mixed |
| Nov | 11 | Mixed |
| Dec | 10 | Mixed |
Humidity comfort
Share of days at each humidity comfort level, based on the dew point — the measure that tracks how muggy it actually feels.
Humidity comfort is graded by the dew point — the temperature at which the air would be fully saturated — because it tracks how muggy it actually feels far better than relative humidity does. A low dew point feels dry and crisp; a high one feels sticky and oppressive no matter the reading on a humidity gauge.
In Olney, how humid it feels changes dramatically over the year.
The more humid part of the year lasts 4.5 months, from around May 19 to October 2. The muggiest month is July, when the air feels humid, muggy or worse about 78% of the time.
The most comfortable stretch runs from around October 3 to May 18, and January is the most comfortable month — the air is dry or comfortable 100% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 99 | 100 | 99 | 90 | 60 | 25 | 9 | 11 | 36 | 76 | 95 | 99 |
| Comfortable (%) | 1 | 0 | 1 | 8 | 18 | 19 | 13 | 15 | 21 | 13 | 4 | 1 |
| Humid (%) | 0 | 0 | 0 | 2 | 15 | 22 | 25 | 24 | 20 | 7 | 1 | 0 |
| Muggy (%) | 0 | 0 | 0 | 0 | 7 | 26 | 35 | 33 | 18 | 3 | 0 | 0 |
| Oppressive (%) | 0 | 0 | 0 | 0 | 0 | 8 | 19 | 16 | 5 | 1 | 0 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | Oppressive (%) | |
|---|---|---|---|---|---|
| Jan | 99 | 1 | 0 | 0 | 0 |
| Feb | 100 | 0 | 0 | 0 | 0 |
| Mar | 99 | 1 | 0 | 0 | 0 |
| Apr | 90 | 8 | 2 | 0 | 0 |
| May | 60 | 18 | 15 | 7 | 0 |
| Jun | 25 | 19 | 22 | 26 | 8 |
| Jul | 9 | 13 | 25 | 35 | 19 |
| Aug | 11 | 15 | 24 | 33 | 16 |
| Sep | 36 | 21 | 20 | 18 | 5 |
| Oct | 76 | 13 | 7 | 3 | 1 |
| Nov | 95 | 4 | 1 | 0 | 0 |
| Dec | 99 | 1 | 0 | 0 | 0 |
Wind
Average wind speed through the year, banded into plain-language speed zones so a number reads as 'breezy' or 'calm' without knowing the scale.
This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.
Across the year, average wind speed in Olney is typically calm, near 7 mph, and varies little with the seasons.
The windier part of the year lasts 6.8 months, from around Oct 17 to May 10. The windiest month is March, averaging about 8 mph (light breeze).
The calmer part of the year runs from around May 11 to Oct 16, with August the calmest month at about 5 mph.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (mph) | 8 | 8 | 8 | 7 | 7 | 6 | 5 | 5 | 6 | 7 | 7 | 7 |
| Feels | light breeze | light breeze | light breeze | light breeze | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (mph) | Feels | |
|---|---|---|
| Jan | 8 | light breeze |
| Feb | 8 | light breeze |
| Mar | 8 | light breeze |
| Apr | 7 | light breeze |
| May | 7 | calm |
| Jun | 6 | calm |
| Jul | 5 | calm |
| Aug | 5 | calm |
| Sep | 6 | calm |
| Oct | 7 | calm |
| Nov | 7 | calm |
| Dec | 7 | calm |
Hazard calendar for Olney
When the seasonal hazards worth planning around — the rainy season, tropical-cyclone risk and dust haze — are active through the year.
Olney sits in the Atlantic hurricane belt; the season peaks August–October.
Best time to visit Olney
To characterize how pleasant the weather is in Olney throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around late April, Olney is still near the start of its best-weather window — great conditions with the peak-season crowds not yet at full swing.
Inferred from the travel-score curve; month-by-month visitor numbers are a planned addition.
The travel score favors clear, rainless days with daytime highs between 64°F and 82°F. Based on this score, the best times of year to visit Olney for general outdoor tourist activities run from mid April to mid June and again from late August to late October, with a peak score in the last week of September.
The travel score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Travel score (0–10) | 0.2 | 0.9 | 3.0 | 5.6 | 6.5 | 5.7 | 4.7 | 5.4 | 6.8 | 6.3 | 3.7 | 1.2 |
| Rating | poor | poor | poor | good | good | good | fair | fair | good | good | fair | poor |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 0.2 | poor |
| Feb | 0.9 | poor |
| Mar | 3.0 | poor |
| Apr | 5.6 | good |
| May | 6.5 | good |
| Jun | 5.7 | good |
| Jul | 4.7 | fair |
| Aug | 5.4 | fair |
| Sep | 6.8 | good |
| Oct | 6.3 | good |
| Nov | 3.7 | fair |
| Dec | 1.2 | poor |
The beach/pool score favors clear, rainless days with daytime highs between 75°F and 93°F. Based on this score, the best time of year to visit Olney for hot-weather activities is from late May to late September, with a peak score in the last week of August.
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
What to pack for Olney, by month
Month by month, what's worth putting in the bag — from the temperature range, rain chance, sun and wind. Tap a month for a quick packing note.
For a warm-season trip around July (highs near 87°F), the essentials are light clothes, rain gear and sun protection. In the cold season around January (highs near 41°F), pack a warm layer, a heavy coat and rain gear.
In July, Olney sees daytime highs around 87°F and nights near 69°F. Pack light clothes and sun protection. Worth having: rain gear. About 12 days see rain.
Sea temperature near Olney
Average ocean temperature at the nearest coast, month by month, banded into swim-comfort zones — the other half of the beach question.
The sea at the nearest coast (about 37 mi away) is warmest in August at about 78°F and coldest in February near 36°F.
It's comfortable for a long swim from Jun 16 to Oct 5 — about 3.7 months when the water holds above 68°F.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°F) | 38 | 36 | 40 | 47 | 58 | 68 | 76 | 78 | 74 | 65 | 53 | 44 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Refreshing | Warm | Warm | Refreshing | Cool | Bracing | Bracing |
| Sea temperature (°F) | Comfort | |
|---|---|---|
| Jan | 38 | Bracing |
| Feb | 36 | Bracing |
| Mar | 40 | Bracing |
| Apr | 47 | Bracing |
| May | 58 | Bracing |
| Jun | 68 | Refreshing |
| Jul | 76 | Warm |
| Aug | 78 | Warm |
| Sep | 74 | Refreshing |
| Oct | 65 | Cool |
| Nov | 53 | Bracing |
| Dec | 44 | Bracing |
UV index (midday) in Olney by month
Clear-sky midday UV index through the year, shaded by the WHO exposure levels — how much sun protection each month calls for.
Under clear skies, the midday UV index in Olney peaks around July 11 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 19 at about 2 (low).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 2 | 3 | 5 | 6 | 8 | 9 | 9 | 7 | 6 | 4 | 3 | 2 |
| Level | Low | Moderate | High | High | Very high | Very high | Very high | High | High | Moderate | Moderate | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 2 | Low |
| Feb | 3 | Moderate |
| Mar | 5 | High |
| Apr | 6 | High |
| May | 8 | Very high |
| Jun | 9 | Very high |
| Jul | 9 | Very high |
| Aug | 7 | High |
| Sep | 6 | High |
| Oct | 4 | Moderate |
| Nov | 3 | Moderate |
| Dec | 2 | Low |
Average hourly UV index in Olney
Modeled clear-sky UV for every hour of every day — when in the day sun protection actually matters.
The whole year hour by hour: each column is a day, each row an hour, and the color is the modeled clear-sky UV index — the midday peak scaled down as the sun sits lower in the sky. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
UV falls off far faster than brightness as the sun drops, so even in July the burn window is concentrated in the middle of the day: about 8.5 hours a day reach index 3 (protection recommended), and 5 hours reach 6 or more. Mornings and late afternoons stay comparatively gentle year round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV ≥ 3 (h/day) | 0 | 1 | 5 | 6.5 | 7.5 | 8 | 8.5 | 7 | 6 | 3 | 0 | 0 |
| UV ≥ 6 (h/day) | 0 | 0 | 0 | 1.5 | 4.5 | 5 | 5 | 3 | 1 | 0 | 0 | 0 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 0 | 0 |
| Feb | 1 | 0 |
| Mar | 5 | 0 |
| Apr | 6.5 | 1.5 |
| May | 7.5 | 4.5 |
| Jun | 8 | 5 |
| Jul | 8.5 | 5 |
| Aug | 7 | 3 |
| Sep | 6 | 1 |
| Oct | 3 | 0 |
| Nov | 0 | 0 |
| Dec | 0 | 0 |
Air quality in Olney by month
Average fine-particle pollution (PM2.5) through the year — so you can see which months the air is worst, not just the yearly average.
Air quality in Olney is worst in July — around 17 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (November, 9 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 11 | 12 | 13 | 13 | 15 | 16 | 17 | 15 | 12 | 9 | 9 | 10 |
| Level | Good | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 11 | Good |
| Feb | 12 | Moderate |
| Mar | 13 | Moderate |
| Apr | 13 | Moderate |
| May | 15 | Moderate |
| Jun | 16 | Moderate |
| Jul | 17 | Moderate |
| Aug | 15 | Moderate |
| Sep | 12 | Moderate |
| Oct | 9 | Good |
| Nov | 9 | Good |
| Dec | 10 | Good |
Growing season
The growing season in Olney typically lasts about 288 days, from around March 2 to December 14 — the span where a frost-free day is more likely than not. It is reliably frost-free from April 4 to November 2.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 32 | 37 | 68 | 96 | 100 | 100 | 100 | 100 | 100 | 98 | 79 | 50 |
| Frost nights | 31 | 28 | 31 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 26 | 31 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 32 | 31 |
| Feb | 37 | 28 |
| Mar | 68 | 31 |
| Apr | 96 | 2 |
| May | 100 | 0 |
| Jun | 100 | 0 |
| Jul | 100 | 0 |
| Aug | 100 | 0 |
| Sep | 100 | 0 |
| Oct | 98 | 0 |
| Nov | 79 | 26 |
| Dec | 50 | 31 |
Growing degree days
Growing degree days tally heat above 50°F: each day adds however many degrees its average temperature runs over that threshold, and cold days add nothing. Olney banks about 3,805 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around July.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°F·days) | 0 | 0 | 0 | 161 | 448 | 707 | 869 | 808 | 572 | 235 | 4 | 0 |
| Growing degree days (°F·days) | |
|---|---|
| Jan | 0 |
| Feb | 0 |
| Mar | 0 |
| Apr | 161 |
| May | 448 |
| Jun | 707 |
| Jul | 869 |
| Aug | 808 |
| Sep | 572 |
| Oct | 235 |
| Nov | 4 |
| Dec | 0 |
Solar energy
Average daily shortwave solar energy reaching the ground, banded into brightness zones so the number means something at a glance.
Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.
Olney receives about 4.1 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 1.9 and 6.3 kWh/m².
The brighter stretch of the year lasts 6.1 months, from around Mar 17 to Sep 19. The brightest month is July, averaging about 6.0 kWh/m² (intense).
The dimmest month is December, down near 1.9 kWh/m² — roughly 68% less than the July peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 2.2 | 3.1 | 4.1 | 5.2 | 5.7 | 6.1 | 6.0 | 5.3 | 4.3 | 3.3 | 2.4 | 1.9 |
| Level | Moderate | Moderate | Bright | Bright | Bright | Intense | Intense | Bright | Bright | Moderate | Moderate | Dim |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 2.2 | Moderate |
| Feb | 3.1 | Moderate |
| Mar | 4.1 | Bright |
| Apr | 5.2 | Bright |
| May | 5.7 | Bright |
| Jun | 6.1 | Intense |
| Jul | 6.0 | Intense |
| Aug | 5.3 | Bright |
| Sep | 4.3 | Bright |
| Oct | 3.3 | Moderate |
| Nov | 2.4 | Moderate |
| Dec | 1.9 | Dim |
Where is Olney?
Olney sits at 39.2°N, 77.1°W, 541 ft above sea level, in United States. The nearest listed city is Redland, 4.3 mi away.
Topography around Olney
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Olney.
Within 2 miles, the terrain around Olney has only modest variations in elevation — a maximum elevation change of 256 ft around an average of 476 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 541 ft; within 50 miles, large variations in elevation — a maximum elevation change of 2,313 ft.
The land around Olney is covered by trees (72%) and grassland (20%) within 2 miles, trees (68%) within 10 miles, and trees (58%) within 50 miles.
United States travel facts
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 100% of US
- price level, 2025
- GDP per capita
- $90,027
- 2025
- Happiness
- 6.8 / 10
- World Happiness, 2025
- Safe drinking water
- 98%
- of population, 2024
- Homicide rate
- 5.8
- per 100k, 2023
- Road deaths
- 12.7
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Olney (39.1532°, -77.0669°, elevation 541 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).