Santa Rosa weather in September
In September, Santa Rosa sees average daytime highs of 81°F and overnight lows near 55°F, with 0.1 in of rain across 0.6 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 10th-wettest month of the year here.
Highs ease over the month, from about 83°F in the first days to 79°F by the end. The sky is clear or mostly clear about 85% of the time in September, and the air most often feels dry.
Daylight stretches from about 12 h 54 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Santa Rosa's 3rd-clearest and 11th-windiest month. For the whole year in context, see Santa Rosa's year-round climate.
- Daytime high
- 81°
- 3rd warmest
- Overnight low
- 55°
- 9th coldest
- Rainfall
- 0.1 in
- 0.6 wet days
- Daylight
- 12 h 12 min
- 5:58 AM – 6:13 PM
- Cloud cover
- 15%
- 3rd clearest
- Wind
- 4 mph
- 11th windiest
- Solar energy
- 5.89 kWh/m²
- Travel score
- 8.6
- out of 10
Santa Rosa is city in and county seat of Sonoma County, California, United States.
- Density
- 1,657/km²
- people per km²
- Founded
- 1868
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Temperature in September
Highs ease over the month, from about 83°F in the first days to 79°F by the end.
A typical September day in Santa Rosa reaches about 81°F in the afternoon and slips back to 55°F overnight — a 26°F spread between the day's warmth and the night's chill. On most days the high lands between 72°F and 91°F. Set against its neighbours, September runs about 2°F cooler than August and about 7°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) | 83 | 83 | 83 | 83 | 83 | 83 | 82 | 82 | 82 | 82 | 82 | 82 | 82 | 81 | 81 | 81 | 81 | 81 | 81 | 81 | 81 | 81 | 80 | 80 | 80 | 80 | 80 | 80 | 79 | 79 |
| Avg low (°F) | 57 | 57 | 56 | 56 | 56 | 56 | 56 | 56 | 56 | 56 | 56 | 55 | 55 | 55 | 55 | 55 | 55 | 55 | 55 | 55 | 55 | 55 | 54 | 54 | 54 | 54 | 54 | 54 | 53 | 53 |
| Avg high (°F) | Avg low (°F) | |
|---|---|---|
| 1 | 83 | 57 |
| 2 | 83 | 57 |
| 3 | 83 | 56 |
| 4 | 83 | 56 |
| 5 | 83 | 56 |
| 6 | 83 | 56 |
| 7 | 82 | 56 |
| 8 | 82 | 56 |
| 9 | 82 | 56 |
| 10 | 82 | 56 |
| 11 | 82 | 56 |
| 12 | 82 | 55 |
| 13 | 82 | 55 |
| 14 | 81 | 55 |
| 15 | 81 | 55 |
| 16 | 81 | 55 |
| 17 | 81 | 55 |
| 18 | 81 | 55 |
| 19 | 81 | 55 |
| 20 | 81 | 55 |
| 21 | 81 | 55 |
| 22 | 81 | 55 |
| 23 | 80 | 54 |
| 24 | 80 | 54 |
| 25 | 80 | 54 |
| 26 | 80 | 54 |
| 27 | 80 | 54 |
| 28 | 80 | 54 |
| 29 | 79 | 53 |
| 30 | 79 | 53 |
Santa Rosa weather by month
How September compares with the rest of the year at a glance. September is the 3rd-warmest and 10th-wettest month here — the current month is highlighted below.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 57° / 40° | 5.7 | 10.3 | 9.6 | 4.0 |
| Feb | 60° / 42° | 5.8 | 9.3 | 10.5 | 4.7 |
| Mar | 63° / 44° | 4.4 | 9.5 | 11.7 | 5.7 |
| Apr | 67° / 46° | 1.9 | 5.6 | 13 | 7.0 |
| May | 73° / 51° | 1.1 | 3.6 | 14.1 | 8.2 |
| Jun | 80° / 55° | 0.3 | 1.2 | 14.6 | 8.5 |
| Jul | 83° / 57° | 0.0 | 0.1 | 14.4 | 7.8 |
| Aug | 83° / 57° | 0.0 | 0.2 | 13.5 | 7.8 |
| Sep | 81° / 55° | 0.1 | 0.6 | 12.3 | 8.6 |
| Oct | 74° / 50° | 1.4 | 3.2 | 11 | 8.5 |
| Nov | 63° / 44° | 3.0 | 6.2 | 9.9 | 6.2 |
| Dec | 56° / 39° | 5.9 | 10.1 | 9.4 | 3.9 |
Cloud cover in September
The sky is clear or mostly clear about 85% of the time in September.
Beyond those clear spells, partly cloudy skies cover about 7% of September, with mostly cloudy or overcast conditions the remaining 8%. Skies tend to cloud over as the month goes on.
| 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 (%) | 95 | 95 | 95 | 95 | 94 | 94 | 94 | 94 | 94 | 93 | 93 | 93 | 93 | 93 | 93 | 93 | 92 | 92 | 92 | 92 | 92 | 91 | 91 | 91 | 90 | 90 | 89 | 89 | 89 | 88 |
| Cloudier (%) | 5 | 5 | 5 | 5 | 6 | 6 | 6 | 6 | 6 | 7 | 7 | 7 | 7 | 7 | 7 | 7 | 8 | 8 | 8 | 8 | 8 | 9 | 9 | 9 | 10 | 10 | 11 | 11 | 11 | 12 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| 1 | 95 | 5 |
| 2 | 95 | 5 |
| 3 | 95 | 5 |
| 4 | 95 | 5 |
| 5 | 94 | 6 |
| 6 | 94 | 6 |
| 7 | 94 | 6 |
| 8 | 94 | 6 |
| 9 | 94 | 6 |
| 10 | 93 | 7 |
| 11 | 93 | 7 |
| 12 | 93 | 7 |
| 13 | 93 | 7 |
| 14 | 93 | 7 |
| 15 | 93 | 7 |
| 16 | 93 | 7 |
| 17 | 92 | 8 |
| 18 | 92 | 8 |
| 19 | 92 | 8 |
| 20 | 92 | 8 |
| 21 | 92 | 8 |
| 22 | 91 | 9 |
| 23 | 91 | 9 |
| 24 | 91 | 9 |
| 25 | 90 | 10 |
| 26 | 90 | 10 |
| 27 | 89 | 11 |
| 28 | 89 | 11 |
| 29 | 89 | 11 |
| 30 | 88 | 12 |
Chance of precipitation in September
Santa Rosa gets around 0.1 in of rain over 0.6 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 3% and peaks near 5% 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 (%) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 2 | 2 | 2 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 4 | 4 | 4 | 5 | 5 | 5 | 5 |
| Rain chance (%) | |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 1 |
| 7 | 1 |
| 8 | 1 |
| 9 | 1 |
| 10 | 1 |
| 11 | 2 |
| 12 | 2 |
| 13 | 2 |
| 14 | 2 |
| 15 | 2 |
| 16 | 2 |
| 17 | 3 |
| 18 | 3 |
| 19 | 3 |
| 20 | 3 |
| 21 | 3 |
| 22 | 3 |
| 23 | 4 |
| 24 | 4 |
| 25 | 4 |
| 26 | 4 |
| 27 | 5 |
| 28 | 5 |
| 29 | 5 |
| 30 | 5 |
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 88% 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 (%) | 81 | 82 | 83 | 84 | 84 | 85 | 85 | 86 | 86 | 86 | 87 | 87 | 87 | 87 | 87 | 88 | 88 | 88 | 89 | 89 | 89 | 89 | 90 | 90 | 91 | 91 | 92 | 92 | 93 | 93 |
| Comfortable (%) | 18 | 17 | 16 | 15 | 15 | 14 | 14 | 13 | 13 | 13 | 12 | 12 | 12 | 12 | 12 | 12 | 12 | 12 | 11 | 11 | 10 | 10 | 9 | 9 | 8 | 8 | 7 | 7 | 6 | 6 |
| Humid (%) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Dry (%) | Comfortable (%) | Humid (%) | |
|---|---|---|---|
| 1 | 81 | 18 | 1 |
| 2 | 82 | 17 | 1 |
| 3 | 83 | 16 | 1 |
| 4 | 84 | 15 | 1 |
| 5 | 84 | 15 | 1 |
| 6 | 85 | 14 | 1 |
| 7 | 85 | 14 | 1 |
| 8 | 86 | 13 | 1 |
| 9 | 86 | 13 | 1 |
| 10 | 86 | 13 | 1 |
| 11 | 87 | 12 | 1 |
| 12 | 87 | 12 | 1 |
| 13 | 87 | 12 | 1 |
| 14 | 87 | 12 | 1 |
| 15 | 87 | 12 | 1 |
| 16 | 88 | 12 | 0 |
| 17 | 88 | 12 | 0 |
| 18 | 88 | 12 | 0 |
| 19 | 89 | 11 | 0 |
| 20 | 89 | 11 | 0 |
| 21 | 89 | 10 | 1 |
| 22 | 89 | 10 | 1 |
| 23 | 90 | 9 | 1 |
| 24 | 90 | 9 | 1 |
| 25 | 91 | 8 | 1 |
| 26 | 91 | 8 | 1 |
| 27 | 92 | 7 | 1 |
| 28 | 92 | 7 | 1 |
| 29 | 93 | 6 | 1 |
| 30 | 93 | 6 | 1 |
Wind in September
Winds average 4 mph in September.
Across September, daily wind ranges from about 4 mph on the calmest days to 4 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) | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 |
| 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 | 4 | calm |
| 2 | 4 | calm |
| 3 | 4 | calm |
| 4 | 4 | calm |
| 5 | 4 | calm |
| 6 | 4 | calm |
| 7 | 4 | calm |
| 8 | 4 | calm |
| 9 | 4 | calm |
| 10 | 4 | calm |
| 11 | 4 | calm |
| 12 | 4 | calm |
| 13 | 4 | calm |
| 14 | 4 | calm |
| 15 | 4 | calm |
| 16 | 4 | calm |
| 17 | 4 | calm |
| 18 | 4 | calm |
| 19 | 4 | calm |
| 20 | 4 | calm |
| 21 | 4 | calm |
| 22 | 4 | calm |
| 23 | 4 | calm |
| 24 | 4 | calm |
| 25 | 4 | calm |
| 26 | 4 | calm |
| 27 | 4 | calm |
| 28 | 4 | calm |
| 29 | 4 | calm |
| 30 | 4 | calm |
Sunrise & sunset in September
Daylight runs from about 12 h 54 min at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.
Days shrink by about 78 minutes over September. Sunrise moves from 5:44 AM to 6:11 AM, and sunset from 6:37 PM to 5:50 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) | 12.9 | 12.8 | 12.8 | 12.8 | 12.7 | 12.7 | 12.6 | 12.6 | 12.5 | 12.5 | 12.5 | 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 | 11.6 |
| Sunrise (AM) | 5:44 | 5:45 | 5:46 | 5:47 | 5:48 | 5:49 | 5:50 | 5:51 | 5:52 | 5:52 | 5:53 | 5:54 | 5:55 | 5:56 | 5:57 | 5:58 | 5:59 | 6:00 | 6:01 | 6:01 | 6:02 | 6:03 | 6:04 | 6:05 | 6:06 | 6:07 | 6:08 | 6:09 | 6:10 | 6:11 |
| Sunset (PM) | 6:37 | 6:35 | 6:34 | 6:32 | 6:30 | 6:29 | 6:27 | 6:26 | 6:24 | 6:22 | 6:21 | 6:19 | 6:17 | 6:16 | 6:14 | 6:13 | 6:11 | 6:09 | 6:08 | 6:06 | 6:04 | 6:03 | 6:01 | 5:59 | 5:58 | 5:56 | 5:54 | 5:53 | 5:51 | 5:50 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| 1 | 12.9 | 5:44 | 6:37 |
| 2 | 12.8 | 5:45 | 6:35 |
| 3 | 12.8 | 5:46 | 6:34 |
| 4 | 12.8 | 5:47 | 6:32 |
| 5 | 12.7 | 5:48 | 6:30 |
| 6 | 12.7 | 5:49 | 6:29 |
| 7 | 12.6 | 5:50 | 6:27 |
| 8 | 12.6 | 5:51 | 6:26 |
| 9 | 12.5 | 5:52 | 6:24 |
| 10 | 12.5 | 5:52 | 6:22 |
| 11 | 12.5 | 5:53 | 6:21 |
| 12 | 12.4 | 5:54 | 6:19 |
| 13 | 12.4 | 5:55 | 6:17 |
| 14 | 12.3 | 5:56 | 6:16 |
| 15 | 12.3 | 5:57 | 6:14 |
| 16 | 12.2 | 5:58 | 6:13 |
| 17 | 12.2 | 5:59 | 6:11 |
| 18 | 12.2 | 6:00 | 6:09 |
| 19 | 12.1 | 6:01 | 6:08 |
| 20 | 12.1 | 6:01 | 6:06 |
| 21 | 12.0 | 6:02 | 6:04 |
| 22 | 12.0 | 6:03 | 6:03 |
| 23 | 11.9 | 6:04 | 6:01 |
| 24 | 11.9 | 6:05 | 5:59 |
| 25 | 11.9 | 6:06 | 5:58 |
| 26 | 11.8 | 6:07 | 5:56 |
| 27 | 11.8 | 6:08 | 5:54 |
| 28 | 11.7 | 6:09 | 5:53 |
| 29 | 11.7 | 6:10 | 5:51 |
| 30 | 11.6 | 6:11 | 5:50 |
Solar energy in September
Average shortwave solar energy reaching the ground each day in September, about 5.89 kWh/m².
For context, solar energy here swings from a low near 2.08 kWh/m² to a high of 8.01 kWh/m² in June across the year — September's 5.89 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) | 6.6 | 6.5 | 6.5 | 6.5 | 6.4 | 6.4 | 6.3 | 6.3 | 6.2 | 6.2 | 6.1 | 6.1 | 6.0 | 6.0 | 5.9 | 5.8 | 5.8 | 5.8 | 5.7 | 5.6 | 5.6 | 5.5 | 5.5 | 5.4 | 5.4 | 5.3 | 5.3 | 5.2 | 5.1 | 5.1 |
| Level | 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 | Bright | Bright | Bright | Bright | Bright |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| 1 | 6.6 | Intense |
| 2 | 6.5 | Intense |
| 3 | 6.5 | Intense |
| 4 | 6.5 | Intense |
| 5 | 6.4 | Intense |
| 6 | 6.4 | Intense |
| 7 | 6.3 | Intense |
| 8 | 6.3 | Intense |
| 9 | 6.2 | Intense |
| 10 | 6.2 | Intense |
| 11 | 6.1 | Intense |
| 12 | 6.1 | Intense |
| 13 | 6.0 | Intense |
| 14 | 6.0 | Bright |
| 15 | 5.9 | Bright |
| 16 | 5.8 | Bright |
| 17 | 5.8 | Bright |
| 18 | 5.8 | Bright |
| 19 | 5.7 | Bright |
| 20 | 5.6 | Bright |
| 21 | 5.6 | Bright |
| 22 | 5.5 | Bright |
| 23 | 5.5 | Bright |
| 24 | 5.4 | Bright |
| 25 | 5.4 | Bright |
| 26 | 5.3 | Bright |
| 27 | 5.3 | Bright |
| 28 | 5.2 | Bright |
| 29 | 5.1 | Bright |
| 30 | 5.1 | Bright |
Hazard calendar for Santa Rosa
None of Santa Rosa's seasonal hazards are active in September. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.
Santa Rosa's rainy season runs November–March, when most of the year's rain falls.
Is September a good time to visit Santa Rosa?
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 Santa Rosa for general sightseeing. The water and warmth also suit a beach or pool day.
What to pack for Santa Rosa in September
From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In September, Santa Rosa sees daytime highs around 81°F and nights near 55°F. Pack light clothes. Worth having: sun protection.
Sea temperature near Santa Rosa in September
The nearest coast averages about 55°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 23 mi away) is warmest in September at about 55°F and coldest in May near 51°F.
The water stays below 68°F all year — cool enough that most swimmers want a wetsuit.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°F) | 53 | 53 | 53 | 51 | 51 | 51 | 53 | 54 | 55 | 55 | 54 | 53 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing |
| Sea temperature (°F) | Comfort | |
|---|---|---|
| Jan | 53 | Bracing |
| Feb | 53 | Bracing |
| Mar | 53 | Bracing |
| Apr | 51 | Bracing |
| May | 51 | Bracing |
| Jun | 51 | Bracing |
| Jul | 53 | Bracing |
| Aug | 54 | Bracing |
| Sep | 55 | Bracing |
| Oct | 55 | Bracing |
| Nov | 54 | Bracing |
| Dec | 53 | Bracing |
UV index in Santa Rosa in September
Clear-sky midday UV in September peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Santa Rosa peaks around June 23 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 17 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) | 2 | 4 | 5 | 6 | 9 | 10 | 10 | 9 | 6 | 5 | 2 | 2 |
| Level | Moderate | Moderate | Moderate | High | Very high | Extreme | Extreme | Very high | High | High | Moderate | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 2 | Moderate |
| Feb | 4 | Moderate |
| Mar | 5 | Moderate |
| Apr | 6 | High |
| May | 9 | Very high |
| Jun | 10 | Extreme |
| Jul | 10 | Extreme |
| Aug | 9 | Very high |
| Sep | 6 | High |
| Oct | 5 | High |
| Nov | 2 | Moderate |
| Dec | 2 | Low |
Air quality in Santa Rosa in September
Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.
Air quality in Santa Rosa is worst in September — around 24 µg/m³ PM2.5 (moderate), about 4.1× the cleanest month (June, 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) | 8 | 9 | 9 | 7 | 7 | 6 | 9 | 17 | 24 | 16 | 9 | 7 |
| Level | Good | Good | Good | Good | Good | Good | Good | Moderate | Moderate | Moderate | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 8 | Good |
| Feb | 9 | Good |
| Mar | 9 | Good |
| Apr | 7 | Good |
| May | 7 | Good |
| Jun | 6 | Good |
| Jul | 9 | Good |
| Aug | 17 | Moderate |
| Sep | 24 | Moderate |
| Oct | 16 | Moderate |
| Nov | 9 | Good |
| Dec | 7 | Good |
Where is Santa Rosa?
Santa Rosa sits at 38.4°N, 122.7°W, 164 ft above sea level, in United States. The nearest listed city is Rohnert Park, 6.8 mi away.
Topography around Santa Rosa
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Santa Rosa.
Within 2 miles, the terrain around Santa Rosa has only modest variations in elevation — a maximum elevation change of 449 ft around an average of 184 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,687 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,895 ft.
The land around Santa Rosa is covered by artificial surfaces (65%) and trees (28%) within 2 miles, trees (44%) and grassland (34%) within 10 miles, and trees (38%), water (27%) and grassland (26%) 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 Santa Rosa (38.4405°, -122.7144°, elevation 164 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. 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).