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Westminster, California climate

BSh Hot semi-arid

Westminster has a mildly seasonal warm-temperate climate (Hot semi-arid, Köppen BSh). The hottest month is August with an average daily high near 29°C, while the coldest is December averaging around 9°C at night. Precipitation totals about 319 mm a year and is strongly seasonal — February alone averages 80 mm while August barely receives 0 mm.

☀️ Summers

Warm

Highs near 29°C in August.

About 29 days a year above 32 °C

❄️ Winters

Cool

Lows near 9°C in December.

🌧️ Rain

Fairly dry

About 319 mm of rain a year.

Wettest in February

⛅ Sky & trend

Fairly sunny

More sun than cloud through the year.

+0.5 °C 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

Westminster climate normals (1991–2020)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°C)	21	21	22	23	24	25	28	29	29	26	23	20
Avg temp (°C)	15	15	16	18	19	21	23	24	23	21	17	15
Avg low (°C)	9	10	11	12	15	16	18	19	18	15	12	9
Precipitation (mm)	73	80	43	21	7	2	1	0	3	13	20	55

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Avg high (°C)	21	21	22	23	24	25
Avg temp (°C)	15	15	16	18	19	21
Avg low (°C)	9	10	11	12	15	16
Precipitation (mm)	73	80	43	21	7	2

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°C)	28	29	29	26	23	20
Avg temp (°C)	23	24	23	21	17	15
Avg low (°C)	18	19	18	15	12	9
Precipitation (mm)	1	0	3	13	20	55

How often — frequency of weather events

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	6	7	5	3	2	0.6	0.5	0.1	0.6	2	3	6
Days with high ≥ 32°C (days)	0.2	0.5	0.8	1	1	1	4	7	7	5	2	0.0
Days with low ≤ 0°C (days)	0.1	—	—	—	—	—	—	0.0	—	—	—	0.1

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Days with measurable rain (days)	6	7	5	3	2	0.6
Days with high ≥ 32°C (days)	0.2	0.5	0.8	1	1	1
Days with low ≤ 0°C (days)	0.1	—	—	—	—	—

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	0.5	0.1	0.6	2	3	6
Days with high ≥ 32°C (days)	4	7	7	5	2	0.0
Days with low ≤ 0°C (days)	—	0.0	—	—	—	0.1

Sky & atmosphere

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	44	46	44	40	43	39	34	27	29	35	34	41
Clear days (≤ 30% cloud)	13	11	12	13	11	11	15	18	17	16	15	14
Partly cloudy days (30–70%)	9	9	12	11	15	15	14	12	10	10	10	9
Cloudy days (≥ 70%)	9	8	8	6	6	4	2	1.0	3	5	5	7
Relative humidity (%)	69	72	75	75	78	79	77	75	74	71	66	67
Wind speed (m/s)	2.8	3.0	2.9	3.0	2.8	2.5	2.3	2.2	2.3	2.4	2.6	2.9

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Cloud cover (%)	44	46	44	40	43	39
Clear days (≤ 30% cloud)	13	11	12	13	11	11
Partly cloudy days (30–70%)	9	9	12	11	15	15
Cloudy days (≥ 70%)	9	8	8	6	6	4
Relative humidity (%)	69	72	75	75	78	79
Wind speed (m/s)	2.8	3.0	2.9	3.0	2.8	2.5

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	34	27	29	35	34	41
Clear days (≤ 30% cloud)	15	18	17	16	15	14
Partly cloudy days (30–70%)	14	12	10	10	10	9
Cloudy days (≥ 70%)	2	1.0	3	5	5	7
Relative humidity (%)	77	75	74	71	66	67
Wind speed (m/s)	2.3	2.2	2.3	2.4	2.6	2.9

Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Santa Ana Fire Stn (NOAA GHCN station USC00047888), about 13 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 →