Weather in San Mateo County

Calculated from weather data of San Francisco International Airport (KSFO) between 2020 and 2024.

Maximum temperatures (°C)

Month	Average	2024	2023	2022	2021	2020
January	14.7	15.0	15.3	14.6	15.3	14.1
February	15.9	15.5	14.4	17.6	17.0	17.6
March	16.5	16.1	14.4	17.6	17.1	16.3
April	18.3		17.3	18.6	18.1	18.1
May	19.6		18.3	20.1	19.6	21.6
June	22.2		20.1	22.8	22.6	23.0
July	21.9		21.6	21.1	21.8	21.8
August	23.2		24.6	23.3	22.5	23.8
September	23.7		22.6	24.6	22.6	24.8
October	22.5		24.1	20.0	20.6	24.8
November	17.8		19.8	16.3	18.1	17.3
December	14.6		16.6	12.5	13.0	15.8
Average	18.8	15.5	19.1	19.3	19.0	19.9

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	8.8	10	9	8	9	9
February	8.3	9	7	8	9	9
March	9.2	10	8	9	9	9
April	10.5		10	10	10	11
May	11.7		12	11	11	12
June	13.5		13	13	15	13
July	13.7		14	14	14	13
August	14.7		16	15	15	15
September	14.8		15	15	14	15
October	12.9		15	12	13	14
November	10.2		12	8	11	9
December	8.6		10	7	9	8
Average	11.2	9.5	11.7	11.0	11.5	11.3

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	7	10	3	13
25 °C or warmer	0	25	28	21	43
20 °C or warmer	2	143	140	141	164
0 °C or colder	0	0	0	0	0

Precipitation (%)

Month	Average	2024	2023	2022	2021	2020
January	9.5	14	17	0	5	3
February	9.6	20	20	0	3	0
March	8.2	11	24	1	2	6
April	1.9		0	2	1	4
May	1.5		3	0	0	2
June	0.1		0	1	0	0
July	0.0		0	0	0	0
August	0.2		1	0	0	1
September	0.2		0	2	0	0
October	0.7		1	0	5	0
November	3.3		2	5	2	1
December	7.1		11	17	12	3
Average	4.5	14.7	6.1	1.6	2.2	1.5

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	12.3	13	16	8	12	13
February	15.6	15	17	13	15	14
March	16.7	18	19	18	17	14
April	20.3		22	23	22	19
May	22.3		19	25	26	20
June	21.8		20	23	23	22
July	22.0		22	23	21	21
August	19.6		19	19	19	19
September	18.3		17	18	18	17
October	14.2		13	16	17	12
November	10.8		10	11	9	13
December	11.0		10	11	13	10
Average	17.2	15.5	17.2	17.9	18.0	16.4

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	SW	SE	E	N	NW
February	S	W	NW	NW	NW
March	W	SW	NW	W	W
April		W	W	W	W
May		W	W	W	W
June		W	NW	W	W
July		NW	NW	NW	NW
August		NW	NW	NW	NW
September		W	NW	NW	NW
October		NW	NW	W	NW
November		NW	W	N	NW
December		SE	S	SW	NW

Prevailing wind direction

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

San Mateo County weather Q&A

What is the warmest month in San Mateo County?

The warmest month is September with an average temperature of 24 °C over the past years.

What is the coldest month in San Mateo County?

The coldest month is December with an average daytime temperature of 15 °C in the past few years.

Which month is the wettest in San Mateo County?

Chance of precipitation is the highest in February with a probability of around 9.7 %.

Which month is the driest in San Mateo County?

The least rainfall and snow can be expected in July. The probability is about 0.0 %.