San Luis Obispo weather in September: San Luis Obispo, California: normal highs, lows, rain and records for September
San Luis Obispo in September has a normal high of 80°F and a normal low of 53°F, a daily mean of 66°F, holding near 80°F all month. Measurable precipitation falls on 1 days in a normal September, 0.04 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 26°C and low of 12°C, 1 mm of precipitation in September.
- NOAA stationSan Luis Obispo Airport
- Station IDUSW00093206
- Location35.24°N 120.64°W
- Elevation200 ft (61 m)
- Population49,729
- Jan 65° 41°
- Feb 65° 42°
- Mar 67° 45°
- Apr 69° 46°
- May 72° 48°
- Jun 75° 51°
- Jul 78° 54°
- Aug 79° 55°
- Sep 80° 53°
- Oct 77° 50°
- Nov 71° 45°
- Dec 65° 40°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is San Luis Obispo in September?
The normal high is 80°F and the normal low 53°F, for a daily mean of 66.4°F. September is 0.7°F cooler than August and 2.9°F warmer than October. September is the 2nd warmest month of the year in San Luis Obispo and the 11th wettest. Across the month the normal high falls 1°F, from 80°F on September 1 to 79°F on September 30. From one year to the next September's mean temperature typically moves about 1.8°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 65°F and 68°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 8%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 80°F | 55°F | 2% | 0% |
| September 8 | 80°F | 54°F | 3% | 0% |
| September 15 | 80°F | 54°F | 4% | 1% |
| September 22 | 79°F | 53°F | 6% | 1% |
| September 30 | 79°F | 52°F | 8% | 2% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 4, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 80°F | 55°F | 2% | 0% | 13 h |
| September 2 | 80°F | 55°F | 2% | 0% | 13 h |
| September 3 | 80°F | 54°F | 2% | 0% | 12 h 50 min |
| September 4 | 80°F | 54°F | 2% | 0% | 12 h 50 min |
| September 5 | 80°F | 54°F | 2% | 0% | 12 h 50 min |
| September 6 | 80°F | 54°F | 2% | 0% | 12 h 50 min |
| September 7 | 80°F | 54°F | 3% | 0% | 12 h 40 min |
| September 8 | 80°F | 54°F | 3% | 0% | 12 h 40 min |
| September 9 | 80°F | 54°F | 3% | 0% | 12 h 40 min |
| September 10 | 80°F | 54°F | 3% | 0% | 12 h 40 min |
| September 11 | 80°F | 54°F | 3% | 1% | 12 h 40 min |
| September 12 | 80°F | 54°F | 3% | 1% | 12 h 30 min |
| September 13 | 80°F | 54°F | 3% | 1% | 12 h 30 min |
| September 14 | 80°F | 54°F | 4% | 1% | 12 h 30 min |
| September 15 | 80°F | 54°F | 4% | 1% | 12 h 30 min |
| September 16 | 80°F | 54°F | 4% | 1% | 12 h 20 min |
| September 17 | 80°F | 53°F | 4% | 1% | 12 h 20 min |
| September 18 | 80°F | 53°F | 4% | 1% | 12 h 20 min |
| September 19 | 80°F | 53°F | 5% | 1% | 12 h 20 min |
| September 20 | 79°F | 53°F | 5% | 1% | 12 h 20 min |
| September 21 | 79°F | 53°F | 5% | 1% | 12 h 10 min |
| September 22 | 79°F | 53°F | 6% | 1% | 12 h 10 min |
| September 23 | 79°F | 53°F | 6% | 1% | 12 h 10 min |
| September 24 | 79°F | 53°F | 6% | 2% | 12 h 10 min |
| September 25 | 79°F | 53°F | 6% | 2% | 12 h 10 min |
| September 26 | 79°F | 52°F | 7% | 2% | 12 h |
| September 27 | 79°F | 52°F | 7% | 2% | 12 h |
| September 28 | 79°F | 52°F | 7% | 2% | 12 h |
| September 29 | 79°F | 52°F | 8% | 2% | 12 h |
| September 30 | 79°F | 52°F | 8% | 2% | 11 h 50 min |
- Normal high
- 80°FSeptember average
- Normal low
- 53°FSeptember average
- Precipitation
- 0.04 inmonth total
- Days with precipitation
- 10.01 inch or more
- Days at 90°F or more
- 4
- Daylight
- 13 h to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 29
- Days at 80°F or more
- 13
- Sunshine
- 95%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00093206; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in San Luis Obispo in September?
On a given September day the chance of 0.01 inch or more is 4% on average, highest around September 30 (8%). In all, 0.04 in falls on 1 days of a normal September.
In a normal September in San Luis Obispo, 4 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00093206.
What are the records for September in San Luis Obispo?
The warmest September temperature on this station's record (since 1998) is 117°F, on September 6, 2020; the coldest is 42°F, on September 29, 2019. The wettest September brought 1.00 in (2022).
The September mean against the 1991-2020 normal of 66.4°F: 2021 67.8°F (+1.4), 2022 71.3°F (+4.9), 2023 68.6°F (+2.2), 2024 70.4°F (+4.0), 2025 68.1°F (+1.7), 2026 67.9°F (+1.5). 6 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 67.8°F | +1.4°F | 0.00 in |
| 2022 | 71.3°F | +4.9°F | 1.00 in |
| 2023 | 68.6°F | +2.2°F | 0.07 in |
| 2024 | 70.4°F | +4.0°F | 0.01 in |
| 2025 | 68.1°F | +1.7°F | 0.36 in |
| 2026 | 67.9°F | +1.5°F | 0.00 in |
Source: records: ACIS, station USW00093206; recent months: ACIS, station USW00093206. Records and recent months use complete months only.
How does September in San Luis Obispo compare across California?
Across the 219 places PlainClimate covers in California, September normal highs run from 64°F in Eureka to 104°F in Brawley; San Luis Obispo's is 80°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.
Other months and places
- San Luis Obispo in August79°F by day, 55°F at night
- San Luis Obispo in October77°F by day, 50°F at night
- San Luis Obispo through the yearEvery month, frost dates, records and recent years
- California in SeptemberThe statewide normal and the warmest and coolest places
- Brawley: California's warmest Septembernormal high 104°F