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Cupertino, California climate

Csb Warm-summer Mediterranean

Cupertino has a mildly seasonal mild-temperate climate (Warm-summer Mediterranean, Köppen Csb). The hottest month is August with an average daily high near 77°F, while the coldest is December averaging around 42°F at night. Precipitation totals about 13 inches a year and is strongly seasonal — February alone averages 2.9 inches while July barely receives 0.00 inches.

☀️ Summers

Mild

Highs near 77°F in August.

About 8 days a year above 90 °F

❄️ Winters

Cool

Lows near 42°F in December.

About 2 freezing nights a year

🌧️ Rain

Fairly dry

About 13 in of rain a year.

Wettest in February

⛅ Sky & trend

Partly cloudy

A roughly even mix of sun and cloud.

−0.1 °F vs 50 years ago

Temperature & precipitation

Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figures

Clear vs cloudy days

Share of days each month that are clear, partly cloudy or cloudy · 1991–2020 · hover a month for the day counts

Cupertino climate normals (1991–2020)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	59	62	65	68	72	76	77	77	78	74	66	59
Avg temp (°F)	51	53	56	58	62	66	68	68	68	64	56	51
Avg low (°F)	42	45	47	49	53	56	59	59	57	53	46	42
Precipitation (in)	2.5	2.9	2.0	1.0	0.4	0.1	0.0	0.0	0.1	0.6	1.4	2.5

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Avg high (°F)	59	62	65	68	72	76
Avg temp (°F)	51	53	56	58	62	66
Avg low (°F)	42	45	47	49	53	56
Precipitation (in)	2.5	2.9	2.0	1.0	0.4	0.1

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	77	77	78	74	66	59
Avg temp (°F)	68	68	68	64	56	51
Avg low (°F)	59	59	57	53	46	42
Precipitation (in)	0.0	0.0	0.1	0.6	1.4	2.5

How often — frequency of weather events

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	9	10	9	5	2	0.9	0.1	0.2	0.7	3	7	9
Days with high ≥ 90°F (days)	—	—	—	0.2	0.7	1	0.9	1	2	0.8	—	—
Days with low ≤ 32°F (days)	1	0.2	—	—	—	—	0.1	0.1	—	—	0.1	0.8

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Days with measurable rain (days)	9	10	9	5	2	0.9
Days with high ≥ 90°F (days)	—	—	—	0.2	0.7	1
Days with low ≤ 32°F (days)	1	0.2	—	—	—	—

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	0.1	0.2	0.7	3	7	9
Days with high ≥ 90°F (days)	0.9	1	2	0.8	—	—
Days with low ≤ 32°F (days)	0.1	0.1	—	—	0.1	0.8

Sky & atmosphere

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	60	61	60	55	54	48	58	59	51	47	51	57
Clear days (≤ 30% cloud)	7	6	7	8	8	10	4	4	9	11	10	8
Partly cloudy days (30–70%)	9	8	11	11	11	11	15	14	11	11	10	9
Cloudy days (≥ 70%)	15	14	14	11	12	9	12	13	10	9	10	14
Relative humidity (%)	84	84	83	79	74	66	62	62	60	63	73	80
Wind speed (mph)	3.8	4.1	4.2	4.8	5.5	6.2	6.2	5.6	4.7	4.0	3.8	4.0

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Cloud cover (%)	60	61	60	55	54	48
Clear days (≤ 30% cloud)	7	6	7	8	8	10
Partly cloudy days (30–70%)	9	8	11	11	11	11
Cloudy days (≥ 70%)	15	14	14	11	12	9
Relative humidity (%)	84	84	83	79	74	66
Wind speed (mph)	3.8	4.1	4.2	4.8	5.5	6.2

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	58	59	51	47	51	57
Clear days (≤ 30% cloud)	4	4	9	11	10	8
Partly cloudy days (30–70%)	15	14	11	11	10	9
Cloudy days (≥ 70%)	12	13	10	9	10	14
Relative humidity (%)	62	62	60	63	73	80
Wind speed (mph)	6.2	5.6	4.7	4.0	3.8	4.0

Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Moffett Fed Airfield (NOAA GHCN station USW00023244), about 9 km from the city centre.

Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.

How we build these numbers →