San Bernardino, CA weather in September
September in San Bernardino: hot and dry. Highs 92°F, lows 60°F, rain on about 1 day. Midday heat is the main thing to plan around.
- Normal high
- 92°F
- Normal low
- 60°F
- Wet days
- 1
- 0.1 in total
- Muggy days
- 1
- dew point 65°F+
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 96°F | 88°F |
| Normal low | 62°F | 57°F |
| Chance of a wet day | 3% | 5% |
| Sunrise / sunset | 6:22 am / 7:15 pm | 6:43 am / 6:35 pm |
| Daylight | 12.9 h | 11.9 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Pacific Time).
A typical September day
- 6 am61°Fdew point 52°F
- 9 am77°Fdew point 52°F
- Noon88°Fdew point 48°F
- 3 pm89°Fdew point 50°F
- 6 pm79°Fdew point 52°F
- 9 pm69°Fdew point 54°F
NOAA hourly normals (local standard time) from March AFB (15 mi away); average wind 5 mph; clear or few clouds in 82% of daytime hours, mostly cloudy or overcast in 12%.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F4 of 30
- Hot dayshigh 90°F or more21 of 30
- Muggy daysdaily mean dew point 65°F or more1 of 30
- Wet daysat least 0.01 in of rain or melted snow1 of 30
- Notable rainat least 0.10 in0 of 30
- Freezing nightslow 32°F or below0 of 30
Average days per September, counted from daily records for each year 1991-2020.
Rain in September
Normal precipitation is 0.1 in; a dry September brings about 0.0 in and a wet one about 0.05 in (25th and 75th percentiles). Days with half an inch or more are rare.
How September varies from year to year
- Warmest September, 1991-20202012: average high 97°F
- Coolest September1998: average high 85°F
- Wettest September1998: 1.1 in
- Driest September1992: no measurable precipitation
- Highest reading110°F (September 1, 2007)
- Lowest reading46°F (September 21, 2007)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
September compared with August and October
| August | September | October | |
|---|---|---|---|
| Normal high | 96°F | 92°F | 83°F |
| Normal low | 63°F | 60°F | 53°F |
| Wet days | 1 | 1 | 3 |
| Comfortable days | 0 | 4 | 12 |
| Daylight | 13.4 h | 12.4 h | 11.3 h |
Highs change by -4°F from August and -9°F into October.
Nearby alternatives in September
- Warmer: Palm Springs, CA47 mi · high 102°F · 1 wet day
- Cooler: Big Bear Lake, CA24 mi · high 73°F · 2 wet days
How San Bernardino ranks in September
- Normal high21st warmest of 378 cities; 7th of 60 in California
- Wet days50th driest of 378
- Comfortable days229th most of 342
What to pack for San Bernardino in September
- Light, breathable clothing – highs near 92°F
- Layers – afternoons near 92°F but nights near 60°F
Heating and cooling
September has 3 heating degree days and 331 cooling degree days (base 65°F), 10% of the year's total heating and cooling demand.
Questions
How hot is San Bernardino in September?
The normal high is 92°F and the normal low is 60°F. From 1991 to 2020 the hottest September reading was 110°F (September 1, 2007).
Does it rain a lot in San Bernardino in September?
About 1 days in September have at least 0.01 in of precipitation, and the normal total is 0.1 in. The wettest September in 1991-2020 was in 1998 (1.2 in); the driest was in 1992, with no measurable precipitation.
Is September a good time to visit San Bernardino?
September ranks 10th of 12 months on our comfort score for San Bernardino (44 out of 100). It has about 4 comfortable days and about 21 days at 90°F or hotter. The best months are March, April and May.
Where the numbers come from
- Temperature, rain, snowfall, snow depth and frost dates: Redlands (USC00047306), 7.3 mi SE of the city center, 1,410 ft (359 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Humidity and wind by hour and cloud cover: March AFB (USW00023119), 15 mi S of the city center, 1,516 ft (465 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: March Air Reserve Base (722860-23119), 15 mi S of the city center, 1,536 ft (485 ft higher than the city). Hourly observations, 1991-2020.