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Casa Grande, Arizona climate

BWh Hot desert

Casa Grande has a seasonal warm-temperate climate (Hot desert, Köppen BWh). The hottest month is July with an average daily high near 42°C, while the coldest is December averaging around 4°C at night. Precipitation totals about 201 mm a year and is strongly seasonal — August alone averages 39 mm while May barely receives 5 mm.

☀️ Summers

Extreme heat

Highs near 42°C in July.

About 152 days a year above 32 °C

❄️ Winters

Chilly

Lows near 4°C in December.

About 14 freezing nights a year

🌧️ Rain

Very dry

About 201 mm of rain a year.

Wettest in August

⛅ Sky & trend

Fairly sunny

More sun than cloud through the year.

+1.1 °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

Casa Grande climate normals (1991–2020)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°C)	20	23	27	31	36	41	42	41	38	33	25	20
Avg temp (°C)	12	14	18	21	26	31	34	33	30	23	16	12
Avg low (°C)	4	5	8	12	16	21	26	25	22	14	7	4
Precipitation (mm)	20	25	19	5	5	5	23	39	18	12	11	19

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Avg high (°C)	20	23	27	31	36	41
Avg temp (°C)	12	14	18	21	26	31
Avg low (°C)	4	5	8	12	16	21
Precipitation (mm)	20	25	19	5	5	5

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°C)	42	41	38	33	25	20
Avg temp (°C)	34	33	30	23	16	12
Avg low (°C)	26	25	22	14	7	4
Precipitation (mm)	23	39	18	12	11	19

How often — frequency of weather events

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	3	4	3	1	1	0.6	3	4	2	2	2	3
Days with high ≥ 32°C (days)	—	—	2	10	22	26	27	24	24	14	2	—
Days with low ≤ 0°C (days)	4	2	0.4	—	—	0.0	—	—	—	0.0	1	6

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Days with measurable rain (days)	3	4	3	1	1	0.6
Days with high ≥ 32°C (days)	—	—	2	10	22	26
Days with low ≤ 0°C (days)	4	2	0.4	—	—	0.0

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	3	4	2	2	2	3
Days with high ≥ 32°C (days)	27	24	24	14	2	—
Days with low ≤ 0°C (days)	—	—	—	0.0	1	6

Sky & atmosphere

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	41	43	37	28	24	21	51	49	30	26	32	41
Clear days (≤ 30% cloud)	14	12	16	19	21	22	8	9	18	21	17	14
Partly cloudy days (30–70%)	9	9	9	8	7	6	13	13	8	6	8	10
Cloudy days (≥ 70%)	7	7	6	3	3	2	10	8	4	4	5	7
Relative humidity (%)	48	46	40	30	23	17	30	36	34	31	36	47
Wind speed (mph)	4.2	4.3	4.4	5.0	5.0	5.1	4.5	3.8	4.1	4.2	4.3	4.1

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Cloud cover (%)	41	43	37	28	24	21
Clear days (≤ 30% cloud)	14	12	16	19	21	22
Partly cloudy days (30–70%)	9	9	9	8	7	6
Cloudy days (≥ 70%)	7	7	6	3	3	2
Relative humidity (%)	48	46	40	30	23	17
Wind speed (mph)	4.2	4.3	4.4	5.0	5.0	5.1

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	51	49	30	26	32	41
Clear days (≤ 30% cloud)	8	9	18	21	17	14
Partly cloudy days (30–70%)	13	13	8	6	8	10
Cloudy days (≥ 70%)	10	8	4	4	5	7
Relative humidity (%)	30	36	34	31	36	47
Wind speed (mph)	4.5	3.8	4.1	4.2	4.3	4.1

Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Casa Grande (NOAA GHCN station USC00021306), about 4 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 →