Climate and average weather in Sun Valley
In Sun Valley, the summers are hot, dry, and clear and the winters are cold, snowy, and partly cloudy.
Over the course of the year, the temperature in Sun Valley typically varies from 21°F to 87°F, and is rarely below 7°F or above 94°F. July is the hottest month of the year, while December is the coldest.
Based on the travel score, the best times of year to visit Sun Valley for warm-weather activities are from late May to early July and late August to mid October.
- Hottest
- Jul
- 87°
- Coldest
- Dec
- 21°
- Wettest
- Jan
- 2.6 in
- Driest
- Aug
- 0.3 in
- Rain / yr
- 16.1 in
- 67 wet days
- Daylight
- 9.2–14.8 h
- shortest–longest
- Elevation
- 4,724 ft
- 39.6°N
- Clearest
- Aug
- 21% cloud
Sun Valley is place in Washoe County, Nevada, USA.
- Density
- 500/km²
- people per km²
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Sun Valley 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 late August to mid October.
Temperature through the year
Daily average highs and lows in Sun Valley, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
The hot season lasts 3.4 months, from June 11 to September 20, with daily high temperatures above 75°F. The hottest month of the year in Sun Valley is July, with an average high of 87°F and low of 56°F.
The cool season lasts 3.6 months, from November 20 to March 8, with daily high temperatures below 48°F. The coldest month of the year in Sun Valley is December, with an average low of 21°F and high of 39°F.
Days typically run about 24°F warmer than nights, with the widest day–night swing (around 30°F) in July.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 40 | 43 | 50 | 57 | 67 | 78 | 87 | 85 | 77 | 64 | 50 | 39 |
| Avg low (°F) | 22 | 24 | 28 | 34 | 42 | 50 | 56 | 56 | 50 | 40 | 29 | 21 |
| Avg high (°F) | Avg low (°F) | |
|---|---|---|
| Jan | 40 | 22 |
| Feb | 43 | 24 |
| Mar | 50 | 28 |
| Apr | 57 | 34 |
| May | 67 | 42 |
| Jun | 78 | 50 |
| Jul | 87 | 56 |
| Aug | 85 | 56 |
| Sep | 77 | 50 |
| Oct | 64 | 40 |
| Nov | 50 | 29 |
| Dec | 39 | 21 |
How hot and cold Sun Valley 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 14°F (around December 20), with roughly 178 freezing days a year (feels-like at or below 32°F), worst in December.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Feels-like high (°F) | 40 | 43 | 50 | 57 | 67 | 78 | 87 | 86 | 77 | 64 | 50 | 39 |
| Air high (°F) | 40 | 43 | 50 | 57 | 67 | 78 | 87 | 85 | 77 | 64 | 50 | 39 |
| Feels-like low (°F) | 17 | 20 | 23 | 29 | 39 | 48 | 56 | 56 | 49 | 37 | 25 | 16 |
| Air low (°F) | 22 | 24 | 28 | 34 | 42 | 50 | 56 | 56 | 50 | 40 | 29 | 21 |
| Feels-like high (°F) | Air high (°F) | Feels-like low (°F) | Air low (°F) | |
|---|---|---|---|---|
| Jan | 40 | 40 | 17 | 22 |
| Feb | 43 | 43 | 20 | 24 |
| Mar | 50 | 50 | 23 | 28 |
| Apr | 57 | 57 | 29 | 34 |
| May | 67 | 67 | 39 | 42 |
| Jun | 78 | 78 | 48 | 50 |
| Jul | 87 | 87 | 56 | 56 |
| Aug | 86 | 85 | 56 | 56 |
| Sep | 77 | 77 | 49 | 50 |
| Oct | 64 | 64 | 37 | 40 |
| Nov | 50 | 50 | 25 | 29 |
| Dec | 39 | 39 | 16 | 21 |
Average hourly temperature in Sun Valley
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 December, near 21°F.
Sun Valley 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 | 40° / 22° | 2.6 | 8 | 6.8 | 9.5 | 0.0 |
| Feb | 43° / 24° | 2.3 | 8.5 | 7.3 | 10.4 | 0.6 |
| Mar | 50° / 28° | 2.2 | 8 | 6 | 11.7 | 2.4 |
| Apr | 57° / 34° | 1.3 | 6.9 | 3.6 | 13 | 4.4 |
| May | 67° / 42° | 1.2 | 6.8 | 1.2 | 14.1 | 6.8 |
| Jun | 78° / 50° | 0.6 | 3.5 | 0.2 | 14.7 | 8.1 |
| Jul | 87° / 56° | 0.4 | 2.8 | 0 | 14.5 | 6.1 |
| Aug | 85° / 56° | 0.3 | 2.7 | 0 | 13.6 | 6.6 |
| Sep | 77° / 50° | 0.4 | 2.5 | 0 | 12.3 | 8.6 |
| Oct | 64° / 40° | 0.9 | 3.5 | 0.8 | 10.9 | 7.0 |
| Nov | 50° / 29° | 1.4 | 5.7 | 3.6 | 9.8 | 2.6 |
| Dec | 39° / 21° | 2.5 | 7.6 | 6.6 | 9.3 | 0.1 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Sun Valley gets about 16.1 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 6.7 months, from around Nov 10 to Jun 1, peaking in February at about 32% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Aug 27.
January is the wettest month by volume, with 2.6 in over about 8 wet days; August is the driest, with 0.3 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 (%) | 26 | 30 | 26 | 23 | 22 | 12 | 9 | 9 | 8 | 11 | 19 | 25 |
| Rain days | 8 | 9 | 8 | 7 | 7 | 4 | 3 | 3 | 3 | 4 | 6 | 8 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 26 | 8 |
| Feb | 30 | 9 |
| Mar | 26 | 8 |
| Apr | 23 | 7 |
| May | 22 | 7 |
| Jun | 12 | 4 |
| Jul | 9 | 3 |
| Aug | 9 | 3 |
| Sep | 8 | 3 |
| Oct | 11 | 4 |
| Nov | 19 | 6 |
| Dec | 25 | 8 |
Monthly rainfall
Over a full year, Sun Valley collects about 16.1 in of rain across 67 wet days — roughly 1.3 in in an average month.
It doesn’t fall evenly. January is the wettest month with 2.6 in, while August is the driest at just 0.3 in. The three wettest months alone bring about 47% 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) | 2.6 | 2.3 | 2.2 | 1.3 | 1.2 | 0.6 | 0.4 | 0.3 | 0.4 | 0.9 | 1.4 | 2.5 |
| Rain days | 8 | 9 | 8 | 7 | 7 | 4 | 3 | 3 | 3 | 4 | 6 | 8 |
| Snow days | 7 | 7 | 6 | 4 | 1 | 0 | 0 | 0 | 0 | 1 | 4 | 7 |
| Rainfall (in) | Rain days | Snow days | |
|---|---|---|---|
| Jan | 2.6 | 8 | 7 |
| Feb | 2.3 | 9 | 7 |
| Mar | 2.2 | 8 | 6 |
| Apr | 1.3 | 7 | 4 |
| May | 1.2 | 7 | 1 |
| Jun | 0.6 | 4 | 0 |
| Jul | 0.4 | 3 | 0 |
| Aug | 0.3 | 3 | 0 |
| Sep | 0.4 | 3 | 0 |
| Oct | 0.9 | 4 | 1 |
| Nov | 1.4 | 6 | 4 |
| Dec | 2.5 | 8 | 7 |
Snow in Sun Valley
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.
Sun Valley averages about 36 snowy days a year. Snow season runs roughly Oct 16 to Jun 3 — about 7.6 months.
February is snowiest, with roughly 8 days of snow and an estimated 20 in of snowfall. Over the year that adds up to an estimated 84 in of snow.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Snow days | 7 | 7 | 6 | 4 | 1 | 0 | 0 | 0 | 0 | 1 | 4 | 7 |
| Snowfall (in) | 18 | 20 | 14 | 7 | 2 | 0 | 0 | 0 | 0 | 1 | 6 | 16 |
| Snow days | Snowfall (in) | |
|---|---|---|
| Jan | 7 | 18 |
| Feb | 7 | 20 |
| Mar | 6 | 14 |
| Apr | 4 | 7 |
| May | 1 | 2 |
| Jun | 0 | 0 |
| Jul | 0 | 0 |
| Aug | 0 | 0 |
| Sep | 0 | 0 |
| Oct | 1 | 1 |
| Nov | 4 | 6 |
| Dec | 7 | 16 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Sun Valley, the average share of the sky covered by clouds shows significant seasonal variation over the course of the year.
The clearer part of the year begins around May 31 and lasts for 5.2 months, ending around November 4. The clearest month is August, when the sky is clear, mostly clear, or partly cloudy 90% of the time on average.
The cloudier part of the year begins around November 5 and lasts for 6.8 months, ending around May 30. The cloudiest month is February, when it is overcast or mostly cloudy 54% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 46 | 46 | 48 | 55 | 62 | 77 | 88 | 90 | 88 | 77 | 59 | 48 |
| Cloudier (%) | 54 | 54 | 52 | 45 | 38 | 23 | 12 | 10 | 12 | 23 | 41 | 52 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 46 | 54 |
| Feb | 46 | 54 |
| Mar | 48 | 52 |
| Apr | 55 | 45 |
| May | 62 | 38 |
| Jun | 77 | 23 |
| Jul | 88 | 12 |
| Aug | 90 | 10 |
| Sep | 88 | 12 |
| Oct | 77 | 23 |
| Nov | 59 | 41 |
| Dec | 48 | 52 |
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 13, brings about 14 h 48 min of light; the shortest, around January 1, 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) | 9.5 | 10.4 | 11.7 | 13.0 | 14.1 | 14.7 | 14.5 | 13.6 | 12.3 | 10.9 | 9.8 | 9.3 |
| Sunrise (AM) | 7:24 | 7:00 | 6:18 | 5:28 | 4:50 | 4:36 | 4:48 | 5:16 | 5:46 | 6:16 | 6:51 | 7:19 |
| Sunset (PM) | 4:53 | 5:27 | 5:59 | 6:31 | 7:00 | 7:23 | 7:21 | 6:50 | 6:01 | 5:12 | 4:38 | 4:32 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 9.5 | 7:24 | 4:53 |
| Feb | 10.4 | 7:00 | 5:27 |
| Mar | 11.7 | 6:18 | 5:59 |
| Apr | 13.0 | 5:28 | 6:31 |
| May | 14.1 | 4:50 | 7:00 |
| Jun | 14.7 | 4:36 | 7:23 |
| Jul | 14.5 | 4:48 | 7:21 |
| Aug | 13.6 | 5:16 | 6:50 |
| Sep | 12.3 | 5:46 | 6:01 |
| Oct | 10.9 | 6:16 | 5:12 |
| Nov | 9.8 | 6:51 | 4:38 |
| Dec | 9.3 | 7:19 | 4:32 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Sun Valley averages about 15 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 9 and 25 days.
The sunnier stretch runs 5.0 months, from around Jun 4 to Nov 3. The sunniest month is August, with roughly 24 sunny days (brilliant).
The greyest month is March, down near 9 sunny days — about 61% fewer than the August peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 10 | 8 | 9 | 11 | 13 | 19 | 23 | 24 | 23 | 20 | 13 | 10 |
| Sky | Mixed | Mixed | Mixed | Mixed | Mixed | Bright | Bright | Brilliant | Brilliant | Bright | Mixed | Mixed |
| Sunny days | Sky | |
|---|---|---|
| Jan | 10 | Mixed |
| Feb | 8 | Mixed |
| Mar | 9 | Mixed |
| Apr | 11 | Mixed |
| May | 13 | Mixed |
| Jun | 19 | Bright |
| Jul | 23 | Bright |
| Aug | 24 | Brilliant |
| Sep | 23 | Brilliant |
| Oct | 20 | Bright |
| Nov | 13 | 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 Sun Valley, the air stays dry or comfortable essentially all year. Even in July, the muggiest month, it feels humid or worse only about 0% of the time — humidity is not something you need to plan around here.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 |
| Dry (%) | |
|---|---|
| Jan | 100 |
| Feb | 100 |
| Mar | 100 |
| Apr | 100 |
| May | 100 |
| Jun | 100 |
| Jul | 100 |
| Aug | 100 |
| Sep | 100 |
| Oct | 100 |
| Nov | 100 |
| Dec | 100 |
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.
Wind in Sun Valley is steady company: average speeds sit near 4 mph — calm — in every month of the year, with no meaningful windy or calm season.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (mph) | 4 | 4 | 4 | 5 | 5 | 5 | 4 | 4 | 4 | 4 | 4 | 4 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (mph) | Feels | |
|---|---|---|
| Jan | 4 | calm |
| Feb | 4 | calm |
| Mar | 4 | calm |
| Apr | 5 | calm |
| May | 5 | calm |
| Jun | 5 | calm |
| Jul | 4 | calm |
| Aug | 4 | calm |
| Sep | 4 | calm |
| Oct | 4 | calm |
| Nov | 4 | calm |
| Dec | 4 | calm |
Best time to visit Sun Valley
To characterize how pleasant the weather is in Sun Valley throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around mid October, Sun Valley 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 Sun Valley for general outdoor tourist activities run from late May to early July and again from late August to mid October, with a peak score in the third 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) | 0.0 | 0.6 | 2.4 | 4.4 | 6.8 | 8.0 | 6.2 | 6.6 | 8.5 | 7.0 | 2.6 | 0.1 |
| Rating | poor | poor | poor | fair | good | ideal | good | good | ideal | good | poor | poor |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 0.0 | poor |
| Feb | 0.6 | poor |
| Mar | 2.4 | poor |
| Apr | 4.4 | fair |
| May | 6.8 | good |
| Jun | 8.0 | ideal |
| Jul | 6.2 | good |
| Aug | 6.6 | good |
| Sep | 8.5 | ideal |
| Oct | 7.0 | good |
| Nov | 2.6 | poor |
| Dec | 0.1 | 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 Sun Valley for hot-weather activities is from mid June 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 Sun Valley, 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 and sun protection. In the cold season around December (highs near 39°F), pack a warm layer and a heavy coat.
In July, Sun Valley sees daytime highs around 87°F and nights near 56°F. Pack light clothes and sun protection.
UV index (midday) in Sun Valley 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 Sun Valley peaks around June 22 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near November 23 at about 2 (moderate).
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) | 3 | 4 | 5 | 7 | 9 | 11 | 11 | 10 | 7 | 5 | 2 | 2 |
| Level | Moderate | Moderate | Moderate | High | Very high | Extreme | Extreme | Very high | High | High | Moderate | Moderate |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 3 | Moderate |
| Feb | 4 | Moderate |
| Mar | 5 | Moderate |
| Apr | 7 | High |
| May | 9 | Very high |
| Jun | 11 | Extreme |
| Jul | 11 | Extreme |
| Aug | 10 | Very high |
| Sep | 7 | High |
| Oct | 5 | High |
| Nov | 2 | Moderate |
| Dec | 2 | Moderate |
Average hourly UV index in Sun Valley
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 9 hours a day reach index 3 (protection recommended), and 6.5 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 | 3.5 | 4.5 | 7 | 8 | 9 | 9 | 8 | 6.5 | 5 | 0 | 0 |
| UV ≥ 6 (h/day) | 0 | 0 | 0 | 3 | 5.5 | 6.5 | 6.5 | 5.5 | 3 | 0 | 0 | 0 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 0 | 0 |
| Feb | 3.5 | 0 |
| Mar | 4.5 | 0 |
| Apr | 7 | 3 |
| May | 8 | 5.5 |
| Jun | 9 | 6.5 |
| Jul | 9 | 6.5 |
| Aug | 8 | 5.5 |
| Sep | 6.5 | 3 |
| Oct | 5 | 0 |
| Nov | 0 | 0 |
| Dec | 0 | 0 |
Air quality in Sun Valley 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 Sun Valley is worst in July — around 51 µg/m³ PM2.5 (poor), about 8.5× the cleanest month (December, 6 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) | 7 | 8 | 10 | 10 | 10 | 10 | 51 | 42 | 45 | 15 | 7 | 6 |
| Level | Good | Good | Good | Good | Good | Good | Poor | Poor | Poor | Moderate | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 7 | Good |
| Feb | 8 | Good |
| Mar | 10 | Good |
| Apr | 10 | Good |
| May | 10 | Good |
| Jun | 10 | Good |
| Jul | 51 | Poor |
| Aug | 42 | Poor |
| Sep | 45 | Poor |
| Oct | 15 | Moderate |
| Nov | 7 | Good |
| Dec | 6 | Good |
Growing season
The growing season in Sun Valley typically lasts about 212 days, from around April 10 to November 7 — the span where a frost-free day is more likely than not. It is reliably frost-free from May 6 to October 16.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 12 | 16 | 31 | 61 | 93 | 100 | 100 | 100 | 99 | 86 | 38 | 13 |
| Frost nights | 31 | 28 | 31 | 30 | 6 | 0 | 0 | 0 | 0 | 16 | 30 | 31 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 12 | 31 |
| Feb | 16 | 28 |
| Mar | 31 | 31 |
| Apr | 61 | 30 |
| May | 93 | 6 |
| Jun | 100 | 0 |
| Jul | 100 | 0 |
| Aug | 100 | 0 |
| Sep | 99 | 0 |
| Oct | 86 | 16 |
| Nov | 38 | 30 |
| Dec | 13 | 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. Sun Valley banks about 2,342 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 | 0 | 132 | 409 | 668 | 640 | 406 | 86 | 0 | 0 |
| Growing degree days (°F·days) | |
|---|---|
| Jan | 0 |
| Feb | 0 |
| Mar | 0 |
| Apr | 0 |
| May | 132 |
| Jun | 409 |
| Jul | 668 |
| Aug | 640 |
| Sep | 406 |
| Oct | 86 |
| Nov | 0 |
| 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.
Sun Valley receives about 5.5 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 2.4 and 8.4 kWh/m².
The brighter stretch of the year lasts 6.3 months, from around Mar 20 to Sep 26. The brightest month is June, averaging about 8.2 kWh/m² (intense).
The dimmest month is December, down near 2.4 kWh/m² — roughly 71% less than the June peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 2.7 | 3.9 | 5.3 | 6.7 | 7.5 | 8.3 | 8.2 | 7.4 | 6.1 | 4.4 | 3.0 | 2.4 |
| Level | Moderate | Moderate | Bright | Intense | Intense | Intense | Intense | Intense | Intense | Bright | Moderate | Moderate |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 2.7 | Moderate |
| Feb | 3.9 | Moderate |
| Mar | 5.3 | Bright |
| Apr | 6.7 | Intense |
| May | 7.5 | Intense |
| Jun | 8.3 | Intense |
| Jul | 8.2 | Intense |
| Aug | 7.4 | Intense |
| Sep | 6.1 | Intense |
| Oct | 4.4 | Bright |
| Nov | 3.0 | Moderate |
| Dec | 2.4 | Moderate |
Where is Sun Valley?
Sun Valley sits at 39.6°N, 119.8°W, 4,724 ft above sea level, in United States. The nearest listed city is Sparks, 4.3 mi away.
Topography around Sun Valley
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Sun Valley.
Within 2 miles, the terrain around Sun Valley has significant variations in elevation — a maximum elevation change of 1,112 ft around an average of 4,898 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,911 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 7,779 ft.
The land around Sun Valley is covered by grassland (51%) and artificial surfaces (31%) within 2 miles, grassland (55%) and artificial surfaces (22%) within 10 miles, and grassland (40%) and trees (29%) 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 Sun Valley (39.5963°, -119.776°, elevation 4,724 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. 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).