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El Cajon, California climate

BSh Hot semi-arid

El Cajon has a mildly seasonal warm-temperate climate (Hot semi-arid, Köppen BSh). The hottest month is August with an average daily high near 31°C, while the coldest is December averaging around 5°C at night. Precipitation totals about 295 mm a year and is strongly seasonal — February alone averages 66 mm while August barely receives 1 mm.

☀️ Summers

Hot

Highs near 31°C in August.

About 47 days a year above 32 °C

❄️ Winters

Cool

Lows near 5°C in December.

About 2 freezing nights a year

🌧️ Rain

Fairly dry

About 295 mm of rain a year.

Wettest in February

⛅ Sky & trend

Fairly sunny

More sun than cloud through the year.

+0.1 °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

El Cajon climate normals (1991–2020)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°C)	21	21	22	24	25	27	30	31	31	27	24	20
Avg temp (°C)	13	14	15	17	19	21	24	25	24	20	16	13
Avg low (°C)	6	7	9	10	13	15	17	18	17	13	8	5
Precipitation (mm)	59	66	49	19	8	2	4	1	3	14	26	46

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Avg high (°C)	21	21	22	24	25	27
Avg temp (°C)	13	14	15	17	19	21
Avg low (°C)	6	7	9	10	13	15
Precipitation (mm)	59	66	49	19	8	2

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°C)	30	31	31	27	24	20
Avg temp (°C)	24	25	24	20	16	13
Avg low (°C)	17	18	17	13	8	5
Precipitation (mm)	4	1	3	14	26	46

How often — frequency of weather events

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	5	7	4	3	2	0.5	0.5	0.3	0.5	1	3	5
Days with high ≥ 32°C (days)	0.1	0.3	0.6	2	2	3	9	13	10	5	2	0.1
Days with low ≤ 0°C (days)	0.8	0.2	—	0.0	0.0	—	—	—	—	0.0	0.2	0.9

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Days with measurable rain (days)	5	7	4	3	2	0.5
Days with high ≥ 32°C (days)	0.1	0.3	0.6	2	2	3
Days with low ≤ 0°C (days)	0.8	0.2	—	0.0	0.0	—

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	0.5	0.3	0.5	1	3	5
Days with high ≥ 32°C (days)	9	13	10	5	2	0.1
Days with low ≤ 0°C (days)	—	—	—	0.0	0.2	0.9

Sky & atmosphere

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	41	46	42	37	35	25	28	24	23	28	33	41
Clear days (≤ 30% cloud)	14	12	13	15	16	21	21	23	22	20	17	14
Partly cloudy days (30–70%)	10	9	10	9	10	7	8	7	6	7	8	10
Cloudy days (≥ 70%)	7	8	8	5	5	2	3	2	2	4	5	7
Relative humidity (%)	63	66	66	64	63	55	49	46	49	53	55	61
Wind speed (m/s)	2.3	2.4	2.4	2.7	2.7	2.5	2.3	2.1	2.0	2.1	2.2	2.3

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Cloud cover (%)	41	46	42	37	35	25
Clear days (≤ 30% cloud)	14	12	13	15	16	21
Partly cloudy days (30–70%)	10	9	10	9	10	7
Cloudy days (≥ 70%)	7	8	8	5	5	2
Relative humidity (%)	63	66	66	64	63	55
Wind speed (m/s)	2.3	2.4	2.4	2.7	2.7	2.5

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	28	24	23	28	33	41
Clear days (≤ 30% cloud)	21	23	22	20	17	14
Partly cloudy days (30–70%)	8	7	6	7	8	10
Cloudy days (≥ 70%)	3	2	2	4	5	7
Relative humidity (%)	49	46	49	53	55	61
Wind speed (m/s)	2.3	2.1	2.0	2.1	2.2	2.3

Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at EL Cajon (NOAA GHCN station USC00042706), about 3 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 →