San Luis Obispo weather in September
In September, San Luis Obispo sees average daytime highs of 72°F and overnight lows near 59°F, with 0.0 in of rain across 0.4 wet days and about 12.2 hours of daylight. It is the 2nd-warmest and 10th-wettest month of the year here.
Day-to-day highs hold fairly steady near 72°F through the month. The sky is clear or mostly clear about 89% of the time in September, and the air most often feels comfortable.
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 San Luis Obispo's 2nd-clearest and 10th-windiest month. For the whole year in context, see San Luis Obispo's year-round climate.
- Daytime high
- 72°
- 2nd warmest
- Overnight low
- 59°
- 11th coldest
- Rainfall
- 0.0 in
- 0.4 wet days
- Daylight
- 12 h 12 min
- 5:50 AM – 6:04 PM
- Cloud cover
- 15%
- 2nd clearest
- Wind
- 5 mph
- 10th windiest
- Solar energy
- 6.15 kWh/m²
- Travel score
- 9.1
- out of 10
San Luis Obispo is county seat of San Luis Obispo County, California, United States.
- Density
- 1,414/km²
- people per km²
- Founded
- 1772
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Temperature in September
Day-to-day highs hold fairly steady near 72°F through the month.
A typical September day in San Luis Obispo reaches about 72°F in the afternoon and slips back to 59°F overnight — a 14°F spread between the day's warmth and the night's chill. On most days the high lands between 66°F and 80°F. Set against its neighbours, September runs on par with August and about 2°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) | 73 | 73 | 73 | 73 | 73 | 73 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 | 72 |
| Avg low (°F) | 59 | 59 | 59 | 59 | 59 | 59 | 59 | 59 | 59 | 59 | 59 | 59 | 59 | 59 | 59 | 58 | 58 | 58 | 58 | 58 | 58 | 58 | 58 | 58 | 58 | 58 | 58 | 58 | 58 | 58 |
| Avg high (°F) | Avg low (°F) | |
|---|---|---|
| 1 | 73 | 59 |
| 2 | 73 | 59 |
| 3 | 73 | 59 |
| 4 | 73 | 59 |
| 5 | 73 | 59 |
| 6 | 73 | 59 |
| 7 | 72 | 59 |
| 8 | 72 | 59 |
| 9 | 72 | 59 |
| 10 | 72 | 59 |
| 11 | 72 | 59 |
| 12 | 72 | 59 |
| 13 | 72 | 59 |
| 14 | 72 | 59 |
| 15 | 72 | 59 |
| 16 | 72 | 58 |
| 17 | 72 | 58 |
| 18 | 72 | 58 |
| 19 | 72 | 58 |
| 20 | 72 | 58 |
| 21 | 72 | 58 |
| 22 | 72 | 58 |
| 23 | 72 | 58 |
| 24 | 72 | 58 |
| 25 | 72 | 58 |
| 26 | 72 | 58 |
| 27 | 72 | 58 |
| 28 | 72 | 58 |
| 29 | 72 | 58 |
| 30 | 72 | 58 |
San Luis Obispo weather by month
How September compares with the rest of the year at a glance. September is the 2nd-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 | 60° / 47° | 3.9 | 7.2 | 9.9 | 5.2 |
| Feb | 60° / 48° | 3.7 | 7.6 | 10.7 | 5.1 |
| Mar | 61° / 49° | 2.8 | 6.2 | 11.7 | 5.8 |
| Apr | 63° / 51° | 1.0 | 3.4 | 12.9 | 6.9 |
| May | 65° / 53° | 0.4 | 1.5 | 13.8 | 7.8 |
| Jun | 69° / 56° | 0.1 | 0.4 | 14.3 | 8.6 |
| Jul | 71° / 58° | 0.0 | 0.1 | 14.1 | 9.0 |
| Aug | 72° / 59° | 0.0 | 0.1 | 13.3 | 9.2 |
| Sep | 72° / 59° | 0.0 | 0.4 | 12.2 | 9.1 |
| Oct | 70° / 56° | 0.8 | 2 | 11.1 | 8.5 |
| Nov | 64° / 51° | 1.3 | 3.6 | 10.1 | 7.1 |
| Dec | 60° / 47° | 3.0 | 6.6 | 9.7 | 5.3 |
Cloud cover in September
The sky is clear or mostly clear about 89% of the time in September.
Beyond those clear spells, partly cloudy skies cover about 5% of September, with mostly cloudy or overcast conditions the remaining 6%. 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 (%) | 97 | 96 | 96 | 96 | 96 | 96 | 95 | 95 | 95 | 95 | 95 | 95 | 95 | 95 | 95 | 94 | 94 | 93 | 93 | 93 | 93 | 93 | 93 | 92 | 92 | 92 | 92 | 92 | 92 | 92 |
| Cloudier (%) | 3 | 4 | 4 | 4 | 4 | 4 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 6 | 6 | 7 | 7 | 7 | 7 | 7 | 7 | 8 | 8 | 8 | 8 | 8 | 8 | 8 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| 1 | 97 | 3 |
| 2 | 96 | 4 |
| 3 | 96 | 4 |
| 4 | 96 | 4 |
| 5 | 96 | 4 |
| 6 | 96 | 4 |
| 7 | 95 | 5 |
| 8 | 95 | 5 |
| 9 | 95 | 5 |
| 10 | 95 | 5 |
| 11 | 95 | 5 |
| 12 | 95 | 5 |
| 13 | 95 | 5 |
| 14 | 95 | 5 |
| 15 | 95 | 5 |
| 16 | 94 | 6 |
| 17 | 94 | 6 |
| 18 | 93 | 7 |
| 19 | 93 | 7 |
| 20 | 93 | 7 |
| 21 | 93 | 7 |
| 22 | 93 | 7 |
| 23 | 93 | 7 |
| 24 | 92 | 8 |
| 25 | 92 | 8 |
| 26 | 92 | 8 |
| 27 | 92 | 8 |
| 28 | 92 | 8 |
| 29 | 92 | 8 |
| 30 | 92 | 8 |
Chance of precipitation in September
San Luis Obispo gets around 0.0 in of rain over 0.4 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 1% and peaks near 3% 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 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 2 | 2 | 2 | 3 | 3 | 3 | 3 |
| Rain chance (%) | |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 1 |
| 7 | 1 |
| 8 | 1 |
| 9 | 1 |
| 10 | 1 |
| 11 | 1 |
| 12 | 1 |
| 13 | 1 |
| 14 | 1 |
| 15 | 1 |
| 16 | 1 |
| 17 | 1 |
| 18 | 1 |
| 19 | 1 |
| 20 | 1 |
| 21 | 2 |
| 22 | 2 |
| 23 | 2 |
| 24 | 2 |
| 25 | 2 |
| 26 | 2 |
| 27 | 3 |
| 28 | 3 |
| 29 | 3 |
| 30 | 3 |
Humidity in September
Most of September feels comfortable — the stacked bands show each day's mix of comfort levels, read off the dew point.
By dew point, September lands in the comfortable band about 59% 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 (%) | 20 | 21 | 22 | 23 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 29 | 30 | 31 | 32 | 32 | 33 | 34 | 35 | 36 | 36 | 37 | 38 | 39 | 40 | 42 | 43 | 45 | 46 | 48 |
| Comfortable (%) | 64 | 63 | 63 | 62 | 63 | 62 | 62 | 62 | 62 | 62 | 62 | 62 | 63 | 62 | 62 | 62 | 61 | 60 | 59 | 58 | 58 | 57 | 57 | 56 | 55 | 53 | 52 | 50 | 49 | 47 |
| Humid (%) | 15 | 15 | 14 | 14 | 13 | 13 | 12 | 11 | 10 | 9 | 8 | 8 | 7 | 7 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 |
| Muggy (%) | 1 | 1 | 1 | 1 | 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 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | |
|---|---|---|---|---|
| 1 | 20 | 64 | 15 | 1 |
| 2 | 21 | 63 | 15 | 1 |
| 3 | 22 | 63 | 14 | 1 |
| 4 | 23 | 62 | 14 | 1 |
| 5 | 23 | 63 | 13 | 1 |
| 6 | 24 | 62 | 13 | 1 |
| 7 | 25 | 62 | 12 | 1 |
| 8 | 26 | 62 | 11 | 1 |
| 9 | 27 | 62 | 10 | 1 |
| 10 | 28 | 62 | 9 | 1 |
| 11 | 29 | 62 | 8 | 1 |
| 12 | 29 | 62 | 8 | 1 |
| 13 | 30 | 63 | 7 | 0 |
| 14 | 31 | 62 | 7 | 0 |
| 15 | 32 | 62 | 6 | 0 |
| 16 | 32 | 62 | 6 | 0 |
| 17 | 33 | 61 | 6 | 0 |
| 18 | 34 | 60 | 6 | 0 |
| 19 | 35 | 59 | 6 | 0 |
| 20 | 36 | 58 | 6 | 0 |
| 21 | 36 | 58 | 6 | 0 |
| 22 | 37 | 57 | 6 | 0 |
| 23 | 38 | 57 | 5 | 0 |
| 24 | 39 | 56 | 5 | 0 |
| 25 | 40 | 55 | 5 | 0 |
| 26 | 42 | 53 | 5 | 0 |
| 27 | 43 | 52 | 5 | 0 |
| 28 | 45 | 50 | 5 | 0 |
| 29 | 46 | 49 | 5 | 0 |
| 30 | 48 | 47 | 5 | 0 |
Wind in September
Winds average 5 mph in September.
Across September, daily wind ranges from about 5 mph on the calmest days to 6 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 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 |
| 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 | 6 | calm |
| 22 | 6 | calm |
| 23 | 6 | calm |
| 24 | 6 | calm |
| 25 | 6 | calm |
| 26 | 6 | calm |
| 27 | 6 | calm |
| 28 | 6 | calm |
| 29 | 6 | calm |
| 30 | 6 | 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 5:39 AM to 6:01 AM, and sunset from 6:26 PM to 5:43 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 | 12.7 | 12.7 | 12.7 | 12.6 | 12.6 | 12.6 | 12.5 | 12.5 | 12.4 | 12.4 | 12.4 | 12.3 | 12.3 | 12.3 | 12.2 | 12.2 | 12.1 | 12.1 | 12.1 | 12.0 | 12.0 | 12.0 | 11.9 | 11.9 | 11.8 | 11.8 | 11.8 | 11.7 | 11.7 |
| Sunrise (AM) | 5:39 | 5:40 | 5:40 | 5:41 | 5:42 | 5:43 | 5:44 | 5:44 | 5:45 | 5:46 | 5:47 | 5:47 | 5:48 | 5:49 | 5:50 | 5:50 | 5:51 | 5:52 | 5:53 | 5:53 | 5:54 | 5:55 | 5:56 | 5:57 | 5:57 | 5:58 | 5:59 | 6:00 | 6:01 | 6:01 |
| Sunset (PM) | 6:26 | 6:24 | 6:23 | 6:21 | 6:20 | 6:18 | 6:17 | 6:16 | 6:14 | 6:13 | 6:11 | 6:10 | 6:08 | 6:07 | 6:05 | 6:04 | 6:02 | 6:00 | 5:59 | 5:57 | 5:56 | 5:54 | 5:53 | 5:51 | 5:50 | 5:48 | 5:47 | 5:45 | 5:44 | 5:43 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| 1 | 12.8 | 5:39 | 6:26 |
| 2 | 12.7 | 5:40 | 6:24 |
| 3 | 12.7 | 5:40 | 6:23 |
| 4 | 12.7 | 5:41 | 6:21 |
| 5 | 12.6 | 5:42 | 6:20 |
| 6 | 12.6 | 5:43 | 6:18 |
| 7 | 12.6 | 5:44 | 6:17 |
| 8 | 12.5 | 5:44 | 6:16 |
| 9 | 12.5 | 5:45 | 6:14 |
| 10 | 12.4 | 5:46 | 6:13 |
| 11 | 12.4 | 5:47 | 6:11 |
| 12 | 12.4 | 5:47 | 6:10 |
| 13 | 12.3 | 5:48 | 6:08 |
| 14 | 12.3 | 5:49 | 6:07 |
| 15 | 12.3 | 5:50 | 6:05 |
| 16 | 12.2 | 5:50 | 6:04 |
| 17 | 12.2 | 5:51 | 6:02 |
| 18 | 12.1 | 5:52 | 6:00 |
| 19 | 12.1 | 5:53 | 5:59 |
| 20 | 12.1 | 5:53 | 5:57 |
| 21 | 12.0 | 5:54 | 5:56 |
| 22 | 12.0 | 5:55 | 5:54 |
| 23 | 12.0 | 5:56 | 5:53 |
| 24 | 11.9 | 5:57 | 5:51 |
| 25 | 11.9 | 5:57 | 5:50 |
| 26 | 11.8 | 5:58 | 5:48 |
| 27 | 11.8 | 5:59 | 5:47 |
| 28 | 11.8 | 6:00 | 5:45 |
| 29 | 11.7 | 6:01 | 5:44 |
| 30 | 11.7 | 6:01 | 5:43 |
Solar energy in September
Average shortwave solar energy reaching the ground each day in September, about 6.15 kWh/m².
For context, solar energy here swings from a low near 2.76 kWh/m² to a high of 8.19 kWh/m² in June across the year — September's 6.15 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) | 6.8 | 6.7 | 6.7 | 6.7 | 6.6 | 6.6 | 6.5 | 6.5 | 6.4 | 6.4 | 6.3 | 6.3 | 6.3 | 6.2 | 6.2 | 6.1 | 6.1 | 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 | Intense | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| 1 | 6.8 | Intense |
| 2 | 6.7 | Intense |
| 3 | 6.7 | Intense |
| 4 | 6.7 | Intense |
| 5 | 6.6 | Intense |
| 6 | 6.6 | Intense |
| 7 | 6.5 | Intense |
| 8 | 6.5 | Intense |
| 9 | 6.4 | Intense |
| 10 | 6.4 | Intense |
| 11 | 6.3 | Intense |
| 12 | 6.3 | Intense |
| 13 | 6.3 | Intense |
| 14 | 6.2 | Intense |
| 15 | 6.2 | Intense |
| 16 | 6.1 | Intense |
| 17 | 6.1 | Intense |
| 18 | 6.0 | Intense |
| 19 | 6.0 | Intense |
| 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 San Luis Obispo?
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 San Luis Obispo for general sightseeing. The water and warmth also suit a beach or pool day.
What to pack for San Luis Obispo in September
From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In September, San Luis Obispo sees daytime highs around 72°F and nights near 59°F. Pack sun protection. Worth having: light clothes.
Sea temperature near San Luis Obispo in September
The nearest coast averages about 60°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 11 mi away) is warmest in September at about 60°F and coldest in April near 54°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) | 56 | 56 | 55 | 54 | 54 | 55 | 58 | 59 | 60 | 60 | 58 | 57 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Cool | Cool | Cool | Bracing | Bracing |
| Sea temperature (°F) | Comfort | |
|---|---|---|
| Jan | 56 | Bracing |
| Feb | 56 | Bracing |
| Mar | 55 | Bracing |
| Apr | 54 | Bracing |
| May | 54 | Bracing |
| Jun | 55 | Bracing |
| Jul | 58 | Bracing |
| Aug | 59 | Cool |
| Sep | 60 | Cool |
| Oct | 60 | Cool |
| Nov | 58 | Bracing |
| Dec | 57 | Bracing |
UV index in San Luis Obispo 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 San Luis Obispo peaks around June 22 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 15 at about 3 (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 | 7 | 8 | 11 | 10 | 10 | 8 | 6 | 3 | 3 |
| 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 | 7 | High |
| May | 8 | Very high |
| Jun | 11 | Extreme |
| Jul | 10 | Extreme |
| Aug | 10 | Extreme |
| Sep | 8 | Very high |
| Oct | 6 | High |
| Nov | 3 | Moderate |
| Dec | 3 | Moderate |
Air quality in San Luis Obispo 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 San Luis Obispo is worst in August — around 19 µg/m³ PM2.5 (moderate), about 4.5× the cleanest month (June, 4 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 | 6 | 7 | 6 | 5 | 4 | 7 | 19 | 17 | 7 | 6 | 5 |
| Level | Good | Good | Good | Good | Good | Good | Good | Moderate | Moderate | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 7 | Good |
| Feb | 6 | Good |
| Mar | 7 | Good |
| Apr | 6 | Good |
| May | 5 | Good |
| Jun | 4 | Good |
| Jul | 7 | Good |
| Aug | 19 | Moderate |
| Sep | 17 | Moderate |
| Oct | 7 | Good |
| Nov | 6 | Good |
| Dec | 5 | Good |
Where is San Luis Obispo?
San Luis Obispo sits at 35.3°N, 120.7°W, 233 ft above sea level, in United States. The nearest listed city is Arroyo Grande, 12 mi away.
Topography around San Luis Obispo
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of San Luis Obispo.
Within 2 miles, the terrain around San Luis Obispo has significant variations in elevation — a maximum elevation change of 1,572 ft around an average of 420 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,861 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 5,407 ft.
The land around San Luis Obispo is covered by grassland (39%), artificial surfaces (36%) and trees (20%) within 2 miles, grassland (44%) and trees (41%) within 10 miles, and grassland (50%) and water (25%) 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 San Luis Obispo (35.2828°, -120.6596°, elevation 233 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).