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Fontana, California climate

BSh Hot semi-arid

Fontana has a seasonal warm-temperate climate (Hot semi-arid, Köppen BSh). The hottest month is August with an average daily high near 97°F, while the coldest is December averaging around 42°F at night. Precipitation totals about 10 inches a year and is strongly seasonal — February alone averages 2.5 inches while June barely receives 0.08 inches.

☀️ Summers

Very hot

Highs near 97°F in August.

About 84 days a year above 90 °F

❄️ Winters

Cool

Lows near 42°F in December.

About 1 freezing nights a year

🌧️ Rain

Fairly dry

About 10 in of rain a year.

Wettest in February

⛅ Sky & trend

Fairly sunny

More sun than cloud through the year.

+1.1 °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

Fontana climate normals (1991–2020)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	70	70	73	78	81	89	95	97	93	84	76	69
Avg temp (°F)	56	57	60	64	68	74	80	81	77	69	61	56
Avg low (°F)	43	44	46	50	55	59	64	65	62	55	47	42
Precipitation (in)	2.2	2.5	1.6	0.6	0.2	0.1	0.1	0.1	0.2	0.4	0.7	1.4

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Avg high (°F)	70	70	73	78	81	89
Avg temp (°F)	56	57	60	64	68	74
Avg low (°F)	43	44	46	50	55	59
Precipitation (in)	2.2	2.5	1.6	0.6	0.2	0.1

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	95	97	93	84	76	69
Avg temp (°F)	80	81	77	69	61	56
Avg low (°F)	64	65	62	55	47	42
Precipitation (in)	0.1	0.1	0.2	0.4	0.7	1.4

How often — frequency of weather events

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	5	5	4	2	1	0.3	0.7	0.3	0.3	1	2	4
Days with high ≥ 90°F (days)	0.2	0.1	1	3	5	11	19	21	15	7	2	0.0
Days with low ≤ 32°F (days)	0.6	0.1	0.0	—	—	—	—	—	—	—	0.1	0.7

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Days with measurable rain (days)	5	5	4	2	1	0.3
Days with high ≥ 90°F (days)	0.2	0.1	1	3	5	11
Days with low ≤ 32°F (days)	0.6	0.1	0.0	—	—	—

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	0.7	0.3	0.3	1	2	4
Days with high ≥ 90°F (days)	19	21	15	7	2	0.0
Days with low ≤ 32°F (days)	—	—	—	—	0.1	0.7

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 (%)	57	61	61	58	56	49	43	39	41	44	47	54
Wind speed (mph)	4.2	4.2	4.1	4.4	4.3	4.2	4.0	3.8	3.6	3.8	3.9	4.3

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 (%)	57	61	61	58	56	49
Wind speed (mph)	4.2	4.2	4.1	4.4	4.3	4.2

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 (%)	43	39	41	44	47	54
Wind speed (mph)	4.0	3.8	3.6	3.8	3.9	4.3

Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Riverside Fire Stn 3 (NOAA GHCN station USC00047470), about 16 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 →