Climate and average weather in Duncan
In Duncan, the summers are humid, sweltering, fairly dry, and mostly clear and the winters are cool and mostly clear.
Over the course of the year, the temperature in Duncan typically varies from 32°F to 94°F, and is rarely below 20°F or above 102°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 Duncan for warm-weather activities are from mid March to late May and late September to mid November.
- Hottest
- Jul
- 94°
- Coldest
- Jan
- 32°
- Wettest
- May
- 4.7 in
- Driest
- Jan
- 1.5 in
- Rain / yr
- 32.5 in
- 81 wet days
- Daylight
- 9.7–14.3 h
- shortest–longest
- Elevation
- 1,122 ft
- 34.5°N
- Clearest
- Oct
- 37% cloud
Duncan is city and county seat of Stephens County, Oklahoma, United States.
- Density
- 188/km²
- people per km²
- Founded
- 1892
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Duncan 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 March to late May.
Temperature through the year
Daily average highs and lows in Duncan, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
The hot season lasts 3.8 months, from May 27 to September 19, with daily high temperatures above 84°F. The hottest month of the year in Duncan is July, with an average high of 94°F and low of 74°F.
The cool season lasts 3.1 months, from November 25 to February 27, with daily high temperatures below 60°F. The coldest month of the year in Duncan is January, with an average low of 32°F and high of 52°F.
Days typically run about 20°F warmer than nights year-round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 52 | 56 | 65 | 73 | 81 | 89 | 94 | 93 | 85 | 74 | 62 | 53 |
| Avg low (°F) | 32 | 36 | 44 | 52 | 62 | 70 | 74 | 73 | 65 | 54 | 42 | 34 |
| Avg high (°F) | Avg low (°F) | |
|---|---|---|
| Jan | 52 | 32 |
| Feb | 56 | 36 |
| Mar | 65 | 44 |
| Apr | 73 | 52 |
| May | 81 | 62 |
| Jun | 89 | 70 |
| Jul | 94 | 74 |
| Aug | 93 | 73 |
| Sep | 85 | 65 |
| Oct | 74 | 54 |
| Nov | 62 | 42 |
| Dec | 53 | 34 |
How hot and cold Duncan 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 hottest afternoons, once humidity is folded in, Duncan feels like about 98°F (around July 18). About 88 days a year carry some heat stress, peaking in July.
On the coldest nights, wind chill pulls the feels-like down to about 25°F (around January 6), with roughly 93 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) | 52 | 56 | 65 | 73 | 81 | 91 | 98 | 96 | 86 | 74 | 62 | 53 |
| Air high (°F) | 52 | 56 | 65 | 73 | 81 | 89 | 94 | 93 | 85 | 74 | 62 | 53 |
| Feels-like low (°F) | 25 | 29 | 39 | 51 | 62 | 70 | 74 | 73 | 65 | 53 | 37 | 27 |
| Air low (°F) | 32 | 36 | 44 | 52 | 62 | 70 | 74 | 73 | 65 | 54 | 42 | 34 |
| Feels-like high (°F) | Air high (°F) | Feels-like low (°F) | Air low (°F) | |
|---|---|---|---|---|
| Jan | 52 | 52 | 25 | 32 |
| Feb | 56 | 56 | 29 | 36 |
| Mar | 65 | 65 | 39 | 44 |
| Apr | 73 | 73 | 51 | 52 |
| May | 81 | 81 | 62 | 62 |
| Jun | 91 | 89 | 70 | 70 |
| Jul | 98 | 94 | 74 | 74 |
| Aug | 96 | 93 | 73 | 73 |
| Sep | 86 | 85 | 65 | 65 |
| Oct | 74 | 74 | 53 | 54 |
| Nov | 62 | 62 | 37 | 42 |
| Dec | 53 | 53 | 27 | 34 |
Average hourly temperature in Duncan
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 94°F, and coldest before dawn in January, near 32°F.
Duncan 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 | 52° / 32° | 1.5 | 4.8 | 0.9 | 10 | 3.2 |
| Feb | 56° / 36° | 1.8 | 5.8 | 0.9 | 10.7 | 4.4 |
| Mar | 65° / 44° | 3.1 | 7.6 | 0.4 | 11.7 | 6.4 |
| Apr | 73° / 52° | 3.6 | 7.9 | 0 | 12.8 | 7.3 |
| May | 81° / 62° | 4.7 | 10.6 | 0 | 13.8 | 6.3 |
| Jun | 89° / 70° | 3.6 | 8.6 | 0 | 14.3 | 4.4 |
| Jul | 94° / 74° | 1.8 | 5.8 | 0 | 14.1 | 3.2 |
| Aug | 93° / 73° | 1.9 | 5.6 | 0 | 13.3 | 3.4 |
| Sep | 85° / 65° | 2.8 | 6.4 | 0 | 12.2 | 5.8 |
| Oct | 74° / 54° | 3.5 | 6.8 | 0 | 11.1 | 7.6 |
| Nov | 62° / 42° | 2.1 | 5.5 | 0.2 | 10.2 | 6.2 |
| Dec | 53° / 34° | 2.0 | 5.2 | 0.8 | 9.7 | 3.5 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Duncan gets about 32.5 in of precipitation a year. On a typical day the chance of rain is some rain, but that rises and falls sharply with the seasons.
The wetter season lasts 4.0 months, from around Mar 7 to Jul 6, peaking in May at about 35% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Jul 21.
May is the wettest month by volume, with 4.7 in over about 11 wet days; January is the driest, with 1.5 in.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 16 | 20 | 24 | 27 | 33 | 30 | 18 | 19 | 22 | 21 | 19 | 17 |
| Rain days | 5 | 6 | 8 | 8 | 11 | 9 | 6 | 6 | 6 | 7 | 6 | 5 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 16 | 5 |
| Feb | 20 | 6 |
| Mar | 24 | 8 |
| Apr | 27 | 8 |
| May | 33 | 11 |
| Jun | 30 | 9 |
| Jul | 18 | 6 |
| Aug | 19 | 6 |
| Sep | 22 | 6 |
| Oct | 21 | 7 |
| Nov | 19 | 6 |
| Dec | 17 | 5 |
Monthly rainfall
Over a full year, Duncan collects about 32.5 in of rain across 81 wet days — roughly 2.7 in in an average month.
It doesn’t fall evenly. May is the wettest month with 4.7 in, while January is the driest at just 1.5 in. The three wettest months alone bring about 37% 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) | 1.5 | 1.8 | 3.1 | 3.6 | 4.7 | 3.6 | 1.8 | 1.9 | 2.8 | 3.5 | 2.1 | 2.0 |
| Rain days | 5 | 6 | 8 | 8 | 11 | 9 | 6 | 6 | 6 | 7 | 6 | 5 |
| Snow days | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Rainfall (in) | Rain days | Snow days | |
|---|---|---|---|
| Jan | 1.5 | 5 | 1 |
| Feb | 1.8 | 6 | 1 |
| Mar | 3.1 | 8 | 0 |
| Apr | 3.6 | 8 | 0 |
| May | 4.7 | 11 | 0 |
| Jun | 3.6 | 9 | 0 |
| Jul | 1.8 | 6 | 0 |
| Aug | 1.9 | 6 | 0 |
| Sep | 2.8 | 6 | 0 |
| Oct | 3.5 | 7 | 0 |
| Nov | 2.1 | 6 | 0 |
| Dec | 2.0 | 5 | 1 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Duncan, 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 10 and lasts for 4.8 months, ending around November 3. The clearest month is July, when the sky is clear, mostly clear, or partly cloudy 77% of the time on average.
The cloudier part of the year begins around November 4 and lasts for 7.2 months, ending around June 9. The cloudiest month is February, when it is overcast or mostly cloudy 45% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 60 | 55 | 57 | 59 | 57 | 67 | 77 | 77 | 72 | 70 | 63 | 59 |
| Cloudier (%) | 40 | 45 | 43 | 41 | 43 | 33 | 23 | 23 | 28 | 30 | 37 | 41 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 60 | 40 |
| Feb | 55 | 45 |
| Mar | 57 | 43 |
| Apr | 59 | 41 |
| May | 57 | 43 |
| Jun | 67 | 33 |
| Jul | 77 | 23 |
| Aug | 77 | 23 |
| Sep | 72 | 28 |
| Oct | 70 | 30 |
| Nov | 63 | 37 |
| Dec | 59 | 41 |
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 10, brings about 14 h 18 min of light; the shortest, around January 1, only 9 h 42 min — a swing of roughly 4 h 36 min.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 10.0 | 10.7 | 11.7 | 12.8 | 13.8 | 14.3 | 14.1 | 13.3 | 12.2 | 11.1 | 10.2 | 9.7 |
| Sunrise (AM) | 7:43 | 7:25 | 6:50 | 6:06 | 5:34 | 5:23 | 5:34 | 5:57 | 6:20 | 6:43 | 7:12 | 7:37 |
| Sunset (PM) | 5:39 | 6:08 | 6:33 | 6:58 | 7:22 | 7:41 | 7:40 | 7:15 | 6:33 | 5:50 | 5:22 | 5:19 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 10.0 | 7:43 | 5:39 |
| Feb | 10.7 | 7:25 | 6:08 |
| Mar | 11.7 | 6:50 | 6:33 |
| Apr | 12.8 | 6:06 | 6:58 |
| May | 13.8 | 5:34 | 7:22 |
| Jun | 14.3 | 5:23 | 7:41 |
| Jul | 14.1 | 5:34 | 7:40 |
| Aug | 13.3 | 5:57 | 7:15 |
| Sep | 12.2 | 6:20 | 6:33 |
| Oct | 11.1 | 6:43 | 5:50 |
| Nov | 10.2 | 7:12 | 5:22 |
| Dec | 9.7 | 7:37 | 5:19 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Duncan averages about 16 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 11 and 20 days.
The sunnier stretch runs 5.4 months, from around Jun 19 to Nov 29. The sunniest month is July, with roughly 19 sunny days (bright).
The greyest month is May, down near 12 sunny days — about 34% fewer than the July peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 15 | 13 | 14 | 14 | 12 | 15 | 19 | 18 | 17 | 18 | 16 | 15 |
| Sky | Mixed | Mixed | Mixed | Mixed | Mixed | Mixed | Bright | Bright | Bright | Bright | Bright | Mixed |
| Sunny days | Sky | |
|---|---|---|
| Jan | 15 | Mixed |
| Feb | 13 | Mixed |
| Mar | 14 | Mixed |
| Apr | 14 | Mixed |
| May | 12 | Mixed |
| Jun | 15 | Mixed |
| Jul | 19 | Bright |
| Aug | 18 | Bright |
| Sep | 17 | Bright |
| Oct | 18 | Bright |
| Nov | 16 | Bright |
| Dec | 15 | 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 Duncan, how humid it feels changes dramatically over the year.
The more humid part of the year lasts 4.8 months, from around May 6 to September 29. The muggiest month is July, when the air feels humid, muggy or worse about 94% of the time.
The most comfortable stretch runs from around September 30 to May 5, 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 | 98 | 90 | 72 | 31 | 4 | 1 | 3 | 26 | 66 | 89 | 98 |
| Comfortable (%) | 1 | 2 | 7 | 15 | 17 | 9 | 6 | 11 | 16 | 16 | 9 | 1 |
| Humid (%) | 0 | 0 | 3 | 11 | 28 | 22 | 24 | 31 | 23 | 11 | 2 | 0 |
| Muggy (%) | 0 | 0 | 0 | 2 | 22 | 50 | 53 | 43 | 29 | 6 | 0 | 0 |
| Oppressive (%) | 0 | 0 | 0 | 0 | 1 | 14 | 16 | 12 | 6 | 0 | 0 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | Oppressive (%) | |
|---|---|---|---|---|---|
| Jan | 99 | 1 | 0 | 0 | 0 |
| Feb | 98 | 2 | 0 | 0 | 0 |
| Mar | 90 | 7 | 3 | 0 | 0 |
| Apr | 72 | 15 | 11 | 2 | 0 |
| May | 31 | 17 | 28 | 22 | 1 |
| Jun | 4 | 9 | 22 | 50 | 14 |
| Jul | 1 | 6 | 24 | 53 | 16 |
| Aug | 3 | 11 | 31 | 43 | 12 |
| Sep | 26 | 16 | 23 | 29 | 6 |
| Oct | 66 | 16 | 11 | 6 | 0 |
| Nov | 89 | 9 | 2 | 0 | 0 |
| Dec | 98 | 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 Duncan is typically light breeze, near 8 mph, and varies moderately with the seasons.
The windier part of the year lasts 4.3 months, from around Feb 9 to Jun 19. The windiest month is April, averaging about 10 mph (light breeze).
The calmer part of the year runs from around Jun 20 to Oct 17, with August the calmest month at about 7 mph.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (mph) | 8 | 9 | 10 | 10 | 9 | 8 | 8 | 7 | 7 | 8 | 9 | 8 |
| Feels | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | calm | light breeze | light breeze | light breeze | light breeze |
| Wind speed (mph) | Feels | |
|---|---|---|
| Jan | 8 | light breeze |
| Feb | 9 | light breeze |
| Mar | 10 | light breeze |
| Apr | 10 | light breeze |
| May | 9 | light breeze |
| Jun | 8 | light breeze |
| Jul | 8 | light breeze |
| Aug | 7 | calm |
| Sep | 7 | light breeze |
| Oct | 8 | light breeze |
| Nov | 9 | light breeze |
| Dec | 8 | light breeze |
Best time to visit Duncan
To characterize how pleasant the weather is in Duncan throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around mid May, Duncan is still near the tail of its best-weather window — great conditions with the peak-season crowds already thinning.
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 Duncan for general outdoor tourist activities run from mid March to late May and again from late September to mid November, with a peak score in the second week of October.
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) | 3.2 | 4.4 | 6.3 | 7.2 | 6.3 | 4.4 | 3.2 | 3.4 | 5.8 | 7.6 | 6.1 | 3.5 |
| Rating | poor | fair | good | good | good | fair | poor | poor | good | ideal | good | fair |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 3.2 | poor |
| Feb | 4.4 | fair |
| Mar | 6.3 | good |
| Apr | 7.2 | good |
| May | 6.3 | good |
| Jun | 4.4 | fair |
| Jul | 3.2 | poor |
| Aug | 3.4 | poor |
| Sep | 5.8 | good |
| Oct | 7.6 | ideal |
| Nov | 6.1 | good |
| Dec | 3.5 | fair |
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 Duncan for hot-weather activities is from late April to mid October, with a peak score in the last week of September.
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 Duncan, 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 94°F), the essentials are light clothes and sun protection. In the cold season around January (highs near 52°F), pack a warm layer.
In July, Duncan sees daytime highs around 94°F and nights near 74°F. Pack light clothes and sun protection. About 6 days see rain.
UV index (midday) in Duncan 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 Duncan peaks around June 23 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 3 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 11 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 3 | 5 | 6 | 9 | 9 | 10 | 10 | 10 | 7 | 6 | 4 | 3 |
| Level | Moderate | Moderate | High | Very high | Very high | Extreme | Extreme | Very high | Very high | High | Moderate | Moderate |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 3 | Moderate |
| Feb | 5 | Moderate |
| Mar | 6 | High |
| Apr | 9 | Very high |
| May | 9 | Very high |
| Jun | 10 | Extreme |
| Jul | 10 | Extreme |
| Aug | 10 | Very high |
| Sep | 7 | Very high |
| Oct | 6 | High |
| Nov | 4 | Moderate |
| Dec | 3 | Moderate |
Average hourly UV index in Duncan
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 June the burn window is concentrated in the middle of the day: about 8.5 hours a day reach index 3 (protection recommended), and 6 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) | 1.5 | 4.5 | 5.5 | 7.5 | 8 | 8.5 | 8.5 | 8 | 6.5 | 5.5 | 3.5 | 0 |
| UV ≥ 6 (h/day) | 0 | 0 | 0 | 5 | 5 | 6 | 5.5 | 5 | 3.5 | 0 | 0 | 0 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 1.5 | 0 |
| Feb | 4.5 | 0 |
| Mar | 5.5 | 0 |
| Apr | 7.5 | 5 |
| May | 8 | 5 |
| Jun | 8.5 | 6 |
| Jul | 8.5 | 5.5 |
| Aug | 8 | 5 |
| Sep | 6.5 | 3.5 |
| Oct | 5.5 | 0 |
| Nov | 3.5 | 0 |
| Dec | 0 | 0 |
Growing season
Duncan is mild enough that a frost-free day stays more likely than not even in midwinter. Nights are reliably above freezing from about March 17 to November 9 (238 days); outside that window a hard frost is an occasional risk.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 51 | 64 | 87 | 98 | 100 | 100 | 100 | 100 | 100 | 99 | 85 | 59 |
| Frost nights | 31 | 28 | 14 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 22 | 31 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 51 | 31 |
| Feb | 64 | 28 |
| Mar | 87 | 14 |
| Apr | 98 | 0 |
| May | 100 | 0 |
| Jun | 100 | 0 |
| Jul | 100 | 0 |
| Aug | 100 | 0 |
| Sep | 100 | 0 |
| Oct | 99 | 0 |
| Nov | 85 | 22 |
| Dec | 59 | 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. Duncan banks about 5,433 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 | 140 | 376 | 657 | 888 | 1,058 | 1,030 | 764 | 435 | 85 | 0 |
| Growing degree days (°F·days) | |
|---|---|
| Jan | 0 |
| Feb | 0 |
| Mar | 140 |
| Apr | 376 |
| May | 657 |
| Jun | 888 |
| Jul | 1,058 |
| Aug | 1,030 |
| Sep | 764 |
| Oct | 435 |
| Nov | 85 |
| 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.
Duncan receives about 4.9 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 2.6 and 7.0 kWh/m².
The brighter stretch of the year lasts 6.2 months, from around Mar 21 to Sep 26. The brightest month is July, averaging about 6.9 kWh/m² (intense).
The dimmest month is December, down near 2.6 kWh/m² — roughly 62% less than the July peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 3.0 | 3.7 | 4.7 | 5.8 | 6.1 | 6.8 | 6.9 | 6.3 | 5.2 | 4.1 | 3.0 | 2.6 |
| Level | Moderate | Moderate | Bright | Bright | Intense | Intense | Intense | Intense | Bright | Bright | Moderate | Moderate |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 3.0 | Moderate |
| Feb | 3.7 | Moderate |
| Mar | 4.7 | Bright |
| Apr | 5.8 | Bright |
| May | 6.1 | Intense |
| Jun | 6.8 | Intense |
| Jul | 6.9 | Intense |
| Aug | 6.3 | Intense |
| Sep | 5.2 | Bright |
| Oct | 4.1 | Bright |
| Nov | 3.0 | Moderate |
| Dec | 2.6 | Moderate |
Where is Duncan?
Duncan sits at 34.5°N, 98.0°W, 1,122 ft above sea level, in United States. The nearest listed city is Lawton, 25 mi away.
Topography around Duncan
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Duncan.
Within 2 miles, the terrain around Duncan has only modest variations in elevation — a maximum elevation change of 167 ft around an average of 1,125 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 367 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 1,716 ft.
The land around Duncan is covered by grassland (39%), trees (29%) and artificial surfaces (27%) within 2 miles, grassland (64%) and trees (25%) within 10 miles, and grassland (66%) 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 Duncan (34.5023°, -97.9578°, elevation 1,122 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. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).