Weather in San Bernardino County

Calculated from weather data of Ontario International Airport (KONT) between 2020 and 2024.

Maximum temperatures (°C)

Month	Average	2024	2023	2022	2021	2020
January	19.1	18.5	15.8	20.1	20.3	20.3
February	19.3	17.1	17.1	22.0	20.8	22.1
March	20.8	18.6	16.8	23.6	20.8	19.1
April	25.2		24.0	25.1	25.5	22.8
May	25.8		22.8	26.6	26.6	29.3
June	30.7		25.3	32.7	33.2	30.3
July	34.9		35.1	33.2	35.6	34.0
August	34.9		34.2	35.2	34.8	36.2
September	32.4		28.5	34.1	33.0	36.0
October	28.9		29.1	27.1	27.6	30.8
November	24.3		24.3	20.6	26.8	24.3
December	19.6		20.8	15.9	16.8	21.1
Average	25.4	18.1	24.5	26.7	26.8	27.2

Average highest temperature per day

The maximum temperature is typically observed some hours after noon.

Minimum temperatures (°C)

Month	Average	2024	2023	2022	2021	2020
January	7.9	8	7	8	8	8
February	8.0	9	6	9	8	9
March	9.6	9	8	10	8	10
April	12.3		11	13	12	13
May	13.7		13	13	14	16
June	16.7		14	18	18	17
July	19.6		20	18	21	18
August	20.2		20	21	21	21
September	18.8		18	21	19	20
October	15.5		15	16	15	17
November	10.8		11	8	12	10
December	8.1		9	6	7	8
Average	12.9	8.4	12.5	13.6	13.5	13.7

Average lowest temperature per day

The minimum temperature is typically observed just before sunrise.

Cold and hot days

Number of days	2024	2023	2022	2021	2020
30 °C or warmer	0	82	120	131	141
25 °C or warmer	2	162	200	206	211
20 °C or warmer	23	250	287	289	290
0 °C or colder	0	0	0	0	0

Precipitation (%)

Month	Average	2024	2023	2022	2021	2020
January	7.3	7	18	1	4	0
February	7.6	19	10	2	2	0
March	8.0	11	23	3	5	7
April	2.3		2	1	2	11
May	2.9		6	1	1	1
June	0.7		2	0	0	2
July	0.2		0	0	1	0
August	0.7		4	0	1	0
September	0.6		2	2	0	0
October	1.3		1	0	6	1
November	2.8		2	6	0	1
December	6.8		4	9	17	2
Average	4.2	12.1	6.2	1.7	3.2	2.1

Precipitation during daylight period

Percentage of observations with observed rain, drizzle, snow or hail. Only observations between sunrise and sunset are taken into account.

Wind speed (km/h)

Month	Average	2024	2023	2022	2021	2020
January	8.5	7	11	8	10	7
February	9.4	7	10	12	9	11
March	10.8	10	10	12	11	11
April	11.5		10	12	12	10
May	11.5		11	11	12	12
June	11.4		10	11	12	12
July	11.1		11	11	12	10
August	11.4		11	12	11	11
September	10.6		10	10	10	10
October	10.4		10	9	10	10
November	8.9		10	10	9	8
December	8.0		6	6	7	9
Average	10.2	8.3	9.9	10.5	10.4	10.3

Average wind speed

Excluding wind gusts. Only observations between sunrise and sunset are taken into account.

Prevailing wind direction

Month	2024	2023	2022	2021	2020
January	W	N	NW	N	W
February	W	W	NW	W	N
March	W	SW	W	SW	SW
April		W	W	W	SW
May		SW	W	W	SW
June		SW	W	W	W
July		W	W	W	W
August		W	W	W	W
September		SW	W	W	W
October		W	SW	W	W
November		N	W	W	W
December		W	SW	W	NW

Prevailing wind direction

Average wind direction, weighed by wind speed. Only observations between sunrise and sunset are taken into account.

San Bernardino County weather Q&A

What is the warmest month in San Bernardino County?

The warmest month is July with an average temperature of 35 °C over the past years.

What is the coldest month in San Bernardino County?

The coldest month is January with an average daytime temperature of 19 °C in the past few years.

Which month is the wettest in San Bernardino County?

Chance of precipitation is the highest in March with a probability of around 8.0 %.

Which month is the driest in San Bernardino County?

The least rainfall and snow can be expected in July. The probability is about 0.3 %.