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San Luis Obispo, California climate

Csb Warm-summer Mediterranean

San Luis Obispo has a mildly seasonal mild-temperate climate (Warm-summer Mediterranean, Köppen Csb). The hottest month is August with an average daily high near 74°F, while the coldest is December averaging around 40°F at night. Precipitation totals about 13 inches a year and is strongly seasonal — February alone averages 2.9 inches while August barely receives 0.01 inches.

☀️ Summers

Mild

Highs near 74°F in August.

About 6 days a year above 90 °F

❄️ Winters

Cool

Lows near 40°F in December.

About 9 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.

+1.0 °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

San Luis Obispo climate normals (1991–2020)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	65	65	66	68	69	71	73	74	75	75	70	64
Avg temp (°F)	53	54	55	57	59	62	64	65	64	62	57	52
Avg low (°F)	41	43	44	45	49	52	55	55	54	50	44	40
Precipitation (in)	2.7	2.9	2.6	0.9	0.4	0.1	0.0	0.0	0.1	0.5	1.1	2.1

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Avg high (°F)	65	65	66	68	69	71
Avg temp (°F)	53	54	55	57	59	62
Avg low (°F)	41	43	44	45	49	52
Precipitation (in)	2.7	2.9	2.6	0.9	0.4	0.1

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	73	74	75	75	70	64
Avg temp (°F)	64	65	64	62	57	52
Avg low (°F)	55	55	54	50	44	40
Precipitation (in)	0.0	0.0	0.1	0.5	1.1	2.1

How often — frequency of weather events

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	8	8	8	4	2	0.6	0.5	0.4	0.6	3	5	7
Days with high ≥ 90°F (days)	—	—	0.1	0.4	0.5	0.4	0.2	0.3	1	2	0.3	—
Days with low ≤ 32°F (days)	3	2	0.4	0.2	—	—	—	—	—	—	0.8	4

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Days with measurable rain (days)	8	8	8	4	2	0.6
Days with high ≥ 90°F (days)	—	—	0.1	0.4	0.5	0.4
Days with low ≤ 32°F (days)	3	2	0.4	0.2	—	—

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	0.5	0.4	0.6	3	5	7
Days with high ≥ 90°F (days)	0.2	0.3	1	2	0.3	—
Days with low ≤ 32°F (days)	—	—	—	—	0.8	4

Sky & atmosphere

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	52	54	52	46	50	53	61	59	54	46	44	50
Clear days (≤ 30% cloud)	10	8	10	10	9	7	3	4	7	12	12	11
Partly cloudy days (30–70%)	10	10	11	12	13	13	16	16	13	11	11	11
Cloudy days (≥ 70%)	11	10	11	7	9	10	11	11	10	8	7	10
Relative humidity (%)	75	77	78	75	72	67	65	64	65	65	69	72
Wind speed (mph)	6.8	7.3	7.1	7.7	7.6	7.2	6.2	6.1	6.0	6.2	6.5	7.0

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Cloud cover (%)	52	54	52	46	50	53
Clear days (≤ 30% cloud)	10	8	10	10	9	7
Partly cloudy days (30–70%)	10	10	11	12	13	13
Cloudy days (≥ 70%)	11	10	11	7	9	10
Relative humidity (%)	75	77	78	75	72	67
Wind speed (mph)	6.8	7.3	7.1	7.7	7.6	7.2

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	61	59	54	46	44	50
Clear days (≤ 30% cloud)	3	4	7	12	12	11
Partly cloudy days (30–70%)	16	16	13	11	11	11
Cloudy days (≥ 70%)	11	11	10	8	7	10
Relative humidity (%)	65	64	65	65	69	72
Wind speed (mph)	6.2	6.1	6.0	6.2	6.5	7.0

Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Santa Maria Public AP (NOAA GHCN station USW00023273), about 47 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 →