San Bernardino climate

Name: San Bernardino
Address: US

San Bernardino is warmest in August, with average highs of 34 °C, and coldest in December, when nights average 5.0 °C. February is the wettest month (91 mm) and June the driest (3.5 mm). Figures are 1991–2020 climate normals.

Across a full year San Bernardino averages 392 mm of rain, 186 days above 25 °C and 5 days below freezing.

United States · 321 m elevation · population 216,108 · 1991–2020 normals

Temperature below 0 °C to above 30 °C Rain band height is that month’s share of the wettest month

Warmest month August 34 °C
Coldest month December 5.0 °C
Driest month June 4 mm
Wettest month February 91 mm
Least cloud August 14 % cloud
Hottest on record September 47 °C
Coldest on record December -4.0 °C

What to expectSan Bernardino through the year

San Bernardino has a clear annual cycle: average daily highs run from 17 °C in December to 34 °C in August, a swing of 16 °C in mean temperature across the year.

Counted across a normal year, 186 days a year reach 25 °C, 115 of them reach 30 °C, 5 nights drop below freezing. The warmest reading in the 1991–2020 record is 47 °C, in September.

Rain is strongly seasonal. February averages 91 mm against 4 mm in June — 26 times as much. Planning around the dry months matters more here than planning around temperature.

Month by month

Month	Avg high	Rainfall	Cloud
January	17.6 °C	76 mm	46 %
February	18.2 °C	91 mm	48 %
March	20.4 °C	56 mm	46 %
April	23.1 °C	28 mm	38 %
May	26.1 °C	13 mm	33 %
June	30.1 °C	4 mm	19 %
July	33.3 °C	10 mm	18 %
August	34.2 °C	8 mm	14 %
September	32.5 °C	7 mm	16 %
October	27.4 °C	18 mm	25 %
November	21.8 °C	25 mm	34 %
December	17.2 °C	56 mm	42 %

Temperature month by month

Month	Avg high	Avg low	Mean	Record high	Record low	Days above 25 °C	Days above 30 °C	Days below 0 °C
January	17.6 °C	5.1 °C	10.4 °C	30.1 °C	-3.8 °C	1	0	2
February	18.2 °C	5.8 °C	11.2 °C	29.6 °C	-2.4 °C	3	0	1
March	20.4 °C	7.5 °C	13.3 °C	33.1 °C	-0.4 °C	6	1	0
April	23.1 °C	9.4 °C	15.6 °C	35.8 °C	0.5 °C	12	3	0
May	26.1 °C	12.4 °C	18.6 °C	38.5 °C	4.4 °C	18	7	0
June	30.1 °C	15.7 °C	22.3 °C	43.7 °C	6.7 °C	26	15	0
July	33.3 °C	19.4 °C	25.8 °C	46.2 °C	11.7 °C	31	26	0
August	34.2 °C	20.0 °C	26.6 °C	43.8 °C	12.6 °C	31	28	0
September	32.5 °C	17.6 °C	24.6 °C	46.7 °C	9.0 °C	28	23	0
October	27.4 °C	13.0 °C	19.6 °C	41.1 °C	2.6 °C	21	10	0
November	21.8 °C	8.3 °C	14.3 °C	34.1 °C	-2.0 °C	8	2	0
December	17.2 °C	5.0 °C	10.2 °C	28.2 °C	-4.0 °C	1	0	2

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind
January	76 mm	6	10 h/day	46 %	62 %	11 km/h
February	91 mm	7	11 h/day	48 %	64 %	11 km/h
March	56 mm	6	12 h/day	46 %	65 %	12 km/h
April	28 mm	4	13 h/day	38 %	60 %	14 km/h
May	13 mm	3	14 h/day	33 %	59 %	14 km/h
June	4 mm	1	14 h/day	19 %	53 %	13 km/h
July	10 mm	2	14 h/day	18 %	50 %	13 km/h
August	8 mm	2	13 h/day	14 %	47 %	13 km/h
September	7 mm	2	12 h/day	16 %	48 %	13 km/h
October	18 mm	3	11 h/day	25 %	49 %	12 km/h
November	25 mm	3	10 h/day	34 %	52 %	11 km/h
December	56 mm	5	9.9 h/day	42 %	59 %	11 km/h

How San Bernardino compares

The same four figures for nearby destinations, so the numbers above have something to be read against. Summer high is the warmest month's average high; winter low is the coldest month's average low.

Destination	Summer high	Winter low	Rain per year	Days above 25 °C
San Bernardino	34 °C	5.0 °C	392 mm	186
Fontana · United States	34 °C	4.8 °C	464 mm	180
Moreno Valley · United States	33 °C	4.6 °C	391 mm	174
Riverside · United States	34 °C	5.0 °C	439 mm	189
Ontario · United States	33 °C	6.4 °C	418 mm	181
Corona · United States	33 °C	6.1 °C	438 mm	189
Pomona · United States	32 °C	6.4 °C	411 mm	176

Where San Bernardino ranks

Ranking	Position	Value
Places with the best weather in North America in April	7thof 50	95/100
Places with the best weather in North America in May	22ndof 50	93/100
The warmest places in North America in September	24thof 50	32 °C
Places with the best weather in North America in November	25thof 50	95/100
The driest places in North America in October	25thof 50	18 mm
The warmest places in North America in August	28thof 50	34 °C

Planning a trip? See the best time to visit San Bernardino.

QuestionsCommon questions about San Bernardino’s climate

When is the best time to visit San Bernardino?

That depends on what you want, so the honest answer is a comparison rather than a single month. May, June, October sit closest to 20 °C on average, August is the warmest month and June the driest. The month-by-month table above has the full picture.

How hot does San Bernardino get?

In August, the warmest month, daily highs average 34 °C. About 115 days a year pass 30 °C. The highest value in the 1991–2020 record is 47 °C.

How cold does it get in winter?

Nights average 5.0 °C in December, the coldest month. A normal year has 5 nights below freezing.

Which month is wettest in San Bernardino?

February, averaging 91 mm over 7 days with rain. The driest month is June with 4 mm. The year as a whole averages 392 mm.

Are these figures a forecast?

No. They are 1991–2020 climate normals: the average of thirty years, which describes what a month is usually like in San Bernardino rather than what any particular week will bring. Individual years can differ substantially from the normal.

Data sources and method

ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
Open-Meteo — Open-Meteo.com. CC BY 4.0
NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
GeoNames — GeoNames.org. CC BY 4.0

Normal period: 1991–2020
Dataset version: era5-1991-2020-scores1.1
Last processed: 1 August 2026

Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: monthly rankings, daylight hours, beach and comfort scores. Full formulas are on the methodology page.

Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.