Washington weather in September
In September, Washington sees average daytime highs of 84°F and overnight lows near 59°F, with 0.4 in of rain across 1.9 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 8th-wettest month of the year here.
Highs ease over the month, from about 88°F in the first days to 80°F by the end. The sky is clear or mostly clear about 80% of the time in September, and the air most often feels dry.
Daylight stretches from about 12 h 48 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Washington's 1st-clearest and 7th-windiest month. For the whole year in context, see Washington's year-round climate.
- Daytime high
- 84°
- 4th warmest
- Overnight low
- 59°
- 9th coldest
- Rainfall
- 0.4 in
- 1.9 wet days
- Daylight
- 12 h 12 min
- 6:21 AM – 6:35 PM
- Cloud cover
- 21%
- 1st clearest
- Wind
- 5 mph
- 7th windiest
- Solar energy
- 6.07 kWh/m²
- Travel score
- 7.2
- out of 10
Washington is city in Washingon County, Utah, United States.
- Density
- 285/km²
- people per km²
- Founded
- 1857
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Temperature in September
Highs ease over the month, from about 88°F in the first days to 80°F by the end.
A typical September day in Washington reaches about 84°F in the afternoon and slips back to 59°F overnight — a 25°F spread between the day's warmth and the night's chill. On most days the high lands between 75°F and 92°F. Set against its neighbours, September runs about 8°F cooler than August and about 13°F warmer than October.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 89 | 89 | 88 | 88 | 88 | 87 | 87 | 87 | 86 | 86 | 85 | 85 | 85 | 85 | 84 | 84 | 84 | 83 | 83 | 83 | 83 | 82 | 82 | 82 | 81 | 81 | 80 | 80 | 80 | 79 |
| Avg low (°F) | 65 | 65 | 64 | 64 | 64 | 63 | 63 | 62 | 62 | 61 | 61 | 60 | 60 | 60 | 59 | 59 | 58 | 58 | 57 | 57 | 57 | 56 | 56 | 55 | 55 | 55 | 54 | 54 | 53 | 53 |
| Avg high (°F) | Avg low (°F) | |
|---|---|---|
| 1 | 89 | 65 |
| 2 | 89 | 65 |
| 3 | 88 | 64 |
| 4 | 88 | 64 |
| 5 | 88 | 64 |
| 6 | 87 | 63 |
| 7 | 87 | 63 |
| 8 | 87 | 62 |
| 9 | 86 | 62 |
| 10 | 86 | 61 |
| 11 | 85 | 61 |
| 12 | 85 | 60 |
| 13 | 85 | 60 |
| 14 | 85 | 60 |
| 15 | 84 | 59 |
| 16 | 84 | 59 |
| 17 | 84 | 58 |
| 18 | 83 | 58 |
| 19 | 83 | 57 |
| 20 | 83 | 57 |
| 21 | 83 | 57 |
| 22 | 82 | 56 |
| 23 | 82 | 56 |
| 24 | 82 | 55 |
| 25 | 81 | 55 |
| 26 | 81 | 55 |
| 27 | 80 | 54 |
| 28 | 80 | 54 |
| 29 | 80 | 53 |
| 30 | 79 | 53 |
How September really feels in Washington
Once humidity and wind are folded in, September averages 0 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.
September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.
Washington weather by month
How September compares with the rest of the year at a glance. September is the 4th-warmest and 8th-wettest month here — the current month is highlighted below.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 48° / 28° | 1.6 | 5.4 | 2.8 | 9.7 | 2.1 |
| Feb | 52° / 31° | 1.8 | 6.3 | 3.1 | 10.6 | 3.2 |
| Mar | 60° / 38° | 1.4 | 5.8 | 1.8 | 11.7 | 5.6 |
| Apr | 68° / 44° | 0.7 | 3.7 | 0.7 | 12.9 | 7.5 |
| May | 78° / 53° | 0.4 | 2.2 | 0 | 14 | 8.3 |
| Jun | 89° / 62° | 0.1 | 0.7 | 0 | 14.5 | 5.6 |
| Jul | 94° / 70° | 0.2 | 1.2 | 0 | 14.3 | 3.7 |
| Aug | 92° / 68° | 0.3 | 1.7 | 0 | 13.4 | 4.3 |
| Sep | 84° / 59° | 0.4 | 1.9 | 0 | 12.3 | 7.2 |
| Oct | 71° / 46° | 0.7 | 2.9 | 0.1 | 11 | 8.3 |
| Nov | 57° / 35° | 0.9 | 3.3 | 0.9 | 10 | 5.1 |
| Dec | 47° / 28° | 1.3 | 4.9 | 2.7 | 9.5 | 1.8 |
Cloud cover in September
The sky is clear or mostly clear about 80% of the time in September, the clearest month of the year.
Beyond those clear spells, partly cloudy skies cover about 9% of September, with mostly cloudy or overcast conditions the remaining 11%.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 87 | 86 | 86 | 86 | 86 | 87 | 87 | 87 | 87 | 89 | 89 | 89 | 89 | 90 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 90 | 90 | 90 | 89 | 88 | 88 | 87 |
| Cloudier (%) | 13 | 14 | 14 | 14 | 14 | 13 | 13 | 13 | 13 | 11 | 11 | 11 | 11 | 10 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 10 | 10 | 10 | 11 | 12 | 12 | 13 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| 1 | 87 | 13 |
| 2 | 86 | 14 |
| 3 | 86 | 14 |
| 4 | 86 | 14 |
| 5 | 86 | 14 |
| 6 | 87 | 13 |
| 7 | 87 | 13 |
| 8 | 87 | 13 |
| 9 | 87 | 13 |
| 10 | 89 | 11 |
| 11 | 89 | 11 |
| 12 | 89 | 11 |
| 13 | 89 | 11 |
| 14 | 90 | 10 |
| 15 | 91 | 9 |
| 16 | 91 | 9 |
| 17 | 91 | 9 |
| 18 | 91 | 9 |
| 19 | 91 | 9 |
| 20 | 91 | 9 |
| 21 | 91 | 9 |
| 22 | 91 | 9 |
| 23 | 91 | 9 |
| 24 | 90 | 10 |
| 25 | 90 | 10 |
| 26 | 90 | 10 |
| 27 | 89 | 11 |
| 28 | 88 | 12 |
| 29 | 88 | 12 |
| 30 | 87 | 13 |
Chance of precipitation in September
Washington gets around 0.4 in of rain over 1.9 wet days in September. The line is the day-by-day chance of measurable precipitation.
Day to day, the chance of measurable rain averages around 7% and peaks near 9% on the wettest days.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain chance (%) | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 8 | 8 | 8 | 7 | 7 | 6 | 6 | 6 | 5 | 5 | 5 | 4 | 4 | 4 | 4 | 4 | 5 | 5 | 5 | 6 | 6 |
| Rain chance (%) | |
|---|---|
| 1 | 9 |
| 2 | 9 |
| 3 | 9 |
| 4 | 9 |
| 5 | 9 |
| 6 | 9 |
| 7 | 9 |
| 8 | 9 |
| 9 | 9 |
| 10 | 8 |
| 11 | 8 |
| 12 | 8 |
| 13 | 7 |
| 14 | 7 |
| 15 | 6 |
| 16 | 6 |
| 17 | 6 |
| 18 | 5 |
| 19 | 5 |
| 20 | 5 |
| 21 | 4 |
| 22 | 4 |
| 23 | 4 |
| 24 | 4 |
| 25 | 4 |
| 26 | 5 |
| 27 | 5 |
| 28 | 5 |
| 29 | 6 |
| 30 | 6 |
Humidity in September
Most of September feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
By dew point, September lands in the dry band about 97% of days. It rarely turns muggy — the humid and sticky bands barely register.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 95 | 95 | 95 | 95 | 95 | 95 | 95 | 95 | 96 | 96 | 97 | 97 | 97 | 97 | 98 | 98 | 98 | 98 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 |
| Comfortable (%) | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 3 | 2 | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Humid (%) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | |
|---|---|---|---|
| 1 | 95 | 4 | 1 |
| 2 | 95 | 4 | 1 |
| 3 | 95 | 4 | 1 |
| 4 | 95 | 4 | 1 |
| 5 | 95 | 4 | 1 |
| 6 | 95 | 4 | 1 |
| 7 | 95 | 4 | 1 |
| 8 | 95 | 4 | 1 |
| 9 | 96 | 4 | 0 |
| 10 | 96 | 4 | 0 |
| 11 | 97 | 3 | 0 |
| 12 | 97 | 3 | 0 |
| 13 | 97 | 3 | 0 |
| 14 | 97 | 3 | 0 |
| 15 | 98 | 2 | 0 |
| 16 | 98 | 2 | 0 |
| 17 | 98 | 2 | 0 |
| 18 | 98 | 2 | 0 |
| 19 | 99 | 1 | 0 |
| 20 | 99 | 1 | 0 |
| 21 | 99 | 1 | 0 |
| 22 | 99 | 1 | 0 |
| 23 | 99 | 1 | 0 |
| 24 | 99 | 1 | 0 |
| 25 | 99 | 1 | 0 |
| 26 | 99 | 1 | 0 |
| 27 | 99 | 1 | 0 |
| 28 | 99 | 1 | 0 |
| 29 | 99 | 1 | 0 |
| 30 | 99 | 1 | 0 |
Wind in September
Winds average 5 mph in September.
Across September, daily wind ranges from about 5 mph on the calmest days to 5 mph at its breeziest. It stays fairly steady from day to day.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (mph) | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (mph) | Feels | |
|---|---|---|
| 1 | 5 | calm |
| 2 | 5 | calm |
| 3 | 5 | calm |
| 4 | 5 | calm |
| 5 | 5 | calm |
| 6 | 5 | calm |
| 7 | 5 | calm |
| 8 | 5 | calm |
| 9 | 5 | calm |
| 10 | 5 | calm |
| 11 | 5 | calm |
| 12 | 5 | calm |
| 13 | 5 | calm |
| 14 | 5 | calm |
| 15 | 5 | calm |
| 16 | 5 | calm |
| 17 | 5 | calm |
| 18 | 5 | calm |
| 19 | 5 | calm |
| 20 | 5 | calm |
| 21 | 5 | calm |
| 22 | 5 | calm |
| 23 | 5 | calm |
| 24 | 5 | calm |
| 25 | 5 | calm |
| 26 | 5 | calm |
| 27 | 5 | calm |
| 28 | 5 | calm |
| 29 | 5 | calm |
| 30 | 5 | calm |
Sunrise & sunset in September
Daylight runs from about 12 h 48 min at the start of September to 11 h 42 min by month's end. The lit band spans sunrise to sunset each day.
Days shrink by about 66 minutes over September. Sunrise moves from 6:09 AM to 6:33 AM, and sunset from 6:59 PM to 6:13 PM.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 12.8 | 12.8 | 12.8 | 12.7 | 12.7 | 12.6 | 12.6 | 12.6 | 12.5 | 12.5 | 12.4 | 12.4 | 12.4 | 12.3 | 12.3 | 12.2 | 12.2 | 12.2 | 12.1 | 12.1 | 12.0 | 12.0 | 11.9 | 11.9 | 11.9 | 11.8 | 11.8 | 11.7 | 11.7 | 11.7 |
| Sunrise (AM) | 6:09 | 6:10 | 6:10 | 6:11 | 6:12 | 6:13 | 6:14 | 6:15 | 6:15 | 6:16 | 6:17 | 6:18 | 6:19 | 6:20 | 6:20 | 6:21 | 6:22 | 6:23 | 6:24 | 6:25 | 6:26 | 6:26 | 6:27 | 6:28 | 6:29 | 6:30 | 6:31 | 6:32 | 6:33 | 6:33 |
| Sunset (PM) | 6:59 | 6:57 | 6:56 | 6:54 | 6:53 | 6:51 | 6:50 | 6:48 | 6:46 | 6:45 | 6:43 | 6:42 | 6:40 | 6:39 | 6:37 | 6:35 | 6:34 | 6:32 | 6:31 | 6:29 | 6:27 | 6:26 | 6:24 | 6:23 | 6:21 | 6:20 | 6:18 | 6:16 | 6:15 | 6:13 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| 1 | 12.8 | 6:09 | 6:59 |
| 2 | 12.8 | 6:10 | 6:57 |
| 3 | 12.8 | 6:10 | 6:56 |
| 4 | 12.7 | 6:11 | 6:54 |
| 5 | 12.7 | 6:12 | 6:53 |
| 6 | 12.6 | 6:13 | 6:51 |
| 7 | 12.6 | 6:14 | 6:50 |
| 8 | 12.6 | 6:15 | 6:48 |
| 9 | 12.5 | 6:15 | 6:46 |
| 10 | 12.5 | 6:16 | 6:45 |
| 11 | 12.4 | 6:17 | 6:43 |
| 12 | 12.4 | 6:18 | 6:42 |
| 13 | 12.4 | 6:19 | 6:40 |
| 14 | 12.3 | 6:20 | 6:39 |
| 15 | 12.3 | 6:20 | 6:37 |
| 16 | 12.2 | 6:21 | 6:35 |
| 17 | 12.2 | 6:22 | 6:34 |
| 18 | 12.2 | 6:23 | 6:32 |
| 19 | 12.1 | 6:24 | 6:31 |
| 20 | 12.1 | 6:25 | 6:29 |
| 21 | 12.0 | 6:26 | 6:27 |
| 22 | 12.0 | 6:26 | 6:26 |
| 23 | 11.9 | 6:27 | 6:24 |
| 24 | 11.9 | 6:28 | 6:23 |
| 25 | 11.9 | 6:29 | 6:21 |
| 26 | 11.8 | 6:30 | 6:20 |
| 27 | 11.8 | 6:31 | 6:18 |
| 28 | 11.7 | 6:32 | 6:16 |
| 29 | 11.7 | 6:33 | 6:15 |
| 30 | 11.7 | 6:33 | 6:13 |
Solar energy in September
Average shortwave solar energy reaching the ground each day in September, about 6.07 kWh/m².
For context, solar energy here swings from a low near 2.73 kWh/m² to a high of 8.49 kWh/m² in June across the year — September's 6.07 kWh/m² falls in the middle.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 6.5 | 6.5 | 6.4 | 6.4 | 6.4 | 6.3 | 6.3 | 6.3 | 6.3 | 6.2 | 6.2 | 6.2 | 6.2 | 6.1 | 6.1 | 6.1 | 6.0 | 6.0 | 6.0 | 6.0 | 5.9 | 5.9 | 5.8 | 5.8 | 5.7 | 5.7 | 5.6 | 5.6 | 5.5 | 5.5 |
| Level | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| 1 | 6.5 | Intense |
| 2 | 6.5 | Intense |
| 3 | 6.4 | Intense |
| 4 | 6.4 | Intense |
| 5 | 6.4 | Intense |
| 6 | 6.3 | Intense |
| 7 | 6.3 | Intense |
| 8 | 6.3 | Intense |
| 9 | 6.3 | Intense |
| 10 | 6.2 | Intense |
| 11 | 6.2 | Intense |
| 12 | 6.2 | Intense |
| 13 | 6.2 | Intense |
| 14 | 6.1 | Intense |
| 15 | 6.1 | Intense |
| 16 | 6.1 | Intense |
| 17 | 6.0 | Intense |
| 18 | 6.0 | Intense |
| 19 | 6.0 | Bright |
| 20 | 6.0 | Bright |
| 21 | 5.9 | Bright |
| 22 | 5.9 | Bright |
| 23 | 5.8 | Bright |
| 24 | 5.8 | Bright |
| 25 | 5.7 | Bright |
| 26 | 5.7 | Bright |
| 27 | 5.6 | Bright |
| 28 | 5.6 | Bright |
| 29 | 5.5 | Bright |
| 30 | 5.5 | Bright |
Is September a good time to visit Washington?
Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).
September is one of the better times to visit Washington for general sightseeing. The water and warmth also suit a beach or pool day.
What to pack for Washington in September
From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In September, Washington sees daytime highs around 84°F and nights near 59°F. Pack light clothes and sun protection.
UV index in Washington in September
Clear-sky midday UV in September peaks around 8 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Washington peaks around July 15 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 18 at about 2 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 3 | 4 | 5 | 6 | 8 | 11 | 11 | 10 | 8 | 6 | 3 | 2 |
| Level | Moderate | Moderate | Moderate | High | Very high | Extreme | Extreme | Extreme | Very high | High | Moderate | Moderate |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 3 | Moderate |
| Feb | 4 | Moderate |
| Mar | 5 | Moderate |
| Apr | 6 | High |
| May | 8 | Very high |
| Jun | 11 | Extreme |
| Jul | 11 | Extreme |
| Aug | 10 | Extreme |
| Sep | 8 | Very high |
| Oct | 6 | High |
| Nov | 3 | Moderate |
| Dec | 2 | Moderate |
Where is Washington?
Washington sits at 37.1°N, 113.5°W, 2,792 ft above sea level, in United States. The nearest listed city is Saint George, 4.3 mi away.
Topography around Washington
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Washington.
Within 2 miles, the terrain around Washington has only modest variations in elevation — a maximum elevation change of 787 ft around an average of 2,854 ft above sea level; within 10 miles, very significant variations in elevation — a maximum elevation change of 4,137 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 9,291 ft.
The land around Washington is covered by artificial surfaces (40%), shrubs (23%) and bare terrain (21%) within 2 miles, grassland (31%), bare terrain (27%) and shrubs (25%) within 10 miles, and shrubs (34%), grassland (28%) and trees (24%) 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 Washington (37.1305°, -113.5083°, elevation 2,792 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).