San Tan Valley climate — normals and trends
San Tan Valley (United States) has a hot desert climate (BWh) under the Köppen-Geiger classification. Its mean annual temperature is 21.7 °C and it receives 271 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (33.2 °C on average) and the coldest is January (10.7 °C). Rainfall peaks in January.
San Tan Valley averages 6 frost days, 173 hot days (≥ 30 °C) and 37 rainy days per year.
San Tan Valley has warmed by +2.7 °C between 1940 and 2025, or +0.31 °C per decade. This trend is statistically significant.
The number of frost days there went from about 12 to 0 per year over the period.
The hottest day of the period reached 47.2 °C (on 26 June 1990) and the coldest -7.2 °C (on 23 December 1990).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
San Tan ValleyArizona
- coords
- 33.19°, -111.53°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
21.7°C
Average daily high
28.5°C
Average daily low
14.9°C
Annual rainfall
271mm
Sunshine / day
11.3h
Mean relative humidity
36%
Average peak wind
14.6km/h
Seasonal range
22.5°C
Frost days (< 0 °C)
6 d/yr
Hot days (≥ 30 °C)
173 d/yr
Rainy days (≥ 1 mm)
37 d/yr
Annual snowfall
0.3 cm
Average feels-like high
26.7 °C
Average feels-like low
12.3 °C
Average peak gust
30.4 km/h
Tropical nights (≥ 20 °C)
120 d/yr
Solar radiation
21.1 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.7 °C
since 1940
+0.3 °C per decade · r² = 0.72 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
47.2 °C
26 June 1990
Coldest day
-7.2 °C
23 December 1990
Wettest day
82 mm
5 September 1970
Windiest day
43.2 km/h
25 April 1984
Strongest gust
92.5 km/h
21 January 2010
Hottest feels-like
47.1 °C
26 June 1990
Coldest feels-like
-12.4 °C
23 December 1990
Snowiest day
3.9 cm
3 February 1985
Sunniest day
14.1 h
23 June 2023
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 17.9 °C | +0.3 °C | 2 mm | -36 mm |
| Feb | 24.2 °C | +4.5 °C | 2 mm | -30 mm |
| Mar | 24.1 °C | +1.2 °C | 43 mm | +12 mm |
| Apr | 28.1 °C | +0.4 °C | 2 mm | -8 mm |
| May | 33.0 °C | +0.3 °C | 2 mm | -2 mm |
| Jun | 39.4 °C | +1.2 °C | 10 mm | +7 mm |
| Jul | 39.6 °C | +0.3 °C | 29 mm | +11 mm |
| Aug | 40.8 °C | +2.8 °C | 4 mm | -27 mm |
| Sep | 35.8 °C | +0.1 °C | 80 mm | +53 mm |
| Oct | 29.2 °C | -0.5 °C | 49 mm | +28 mm |
| Nov | 24.3 °C | +1.6 °C | 49 mm | +27 mm |
| Dec | 21.8 °C | +3.9 °C | 4 mm | -31 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of San Tan Valley?
San Tan Valley has a hot desert climate (Köppen BWh). Over 1940-2025, the average annual temperature is 21.7 °C and it receives 271 mm of precipitation per year.
What is the hottest day ever recorded in San Tan Valley?
The hottest day measured in San Tan Valley between 1940 and 2025 was 26 June 1990, reaching 47.2 °C.
What is the coldest day in San Tan Valley?
The coldest day measured in San Tan Valley between 1940 and 2025 was 23 December 1990, at -7.2 °C.
Does it snow in San Tan Valley?
Almost never: San Tan Valley sees virtually no snow, with about 6 frost days per year.
Has the climate of San Tan Valley warmed?
Yes: San Tan Valley warmed by +2.7 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in San Tan Valley?
The wettest day measured in San Tan Valley between 1940 and 2025 was 5 September 1970, with 82 mm of rain in 24 hours.
What was the windiest day in San Tan Valley?
The windiest day measured in San Tan Valley between 1940 and 2025 was 25 April 1984, with winds reaching 43.2 km/h.
What is the warmest month in San Tan Valley?
The warmest month in San Tan Valley is July (33.2 °C on average); the coldest is January (10.7 °C).
How much does it rain in San Tan Valley?
San Tan Valley receives on average 271 mm of precipitation per year, spread over about 37 rainy days.
Is it sunny in San Tan Valley?
San Tan Valley gets on average 11.3 hours of sunshine per day, roughly 4,125 hours per year over 1940-2025.
What is the biggest single-day snowfall in San Tan Valley?
The heaviest 24-hour snowfall measured in San Tan Valley between 1940 and 2025 was 3 February 1985, with 3.9 cm.
Are there tropical nights in San Tan Valley?
Yes: San Tan Valley has on average 120 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in San Tan Valley?
In San Tan Valley, between 1940 and 2025, the highest apparent temperature reached 47.1 °C on 26 June 1990, and the lowest was -12.4 °C on 23 December 1990.
Compare San Tan Valley with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around San Tan Valley