San Tan Valley weather by month
What a typical year looks like in San Tan Valley, Arizona: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at CASA GRANDE NATL MONUMENT, 21 km from San Tan Valley; records cover 1908–2026.
The year at a glance
- Precipitation a year
- 8.3 in210 mm
- Snow a year
- Rare
- Last spring freeze
- Feb 25
- First fall freeze
- Nov 24
- Heating degree days
- 1,452
- Cooling degree days
- 3,775
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are 25°−4° (heating, 99%) and 115°46° (cooling, 1%).
Month by month
San Tan Valley in January
Highs average 68°20° and lows 37°3°, with 0.98 in25 mm of precipitation in a typical January.
- Record high
- 89°32° (1935)
- Record low
- 8°−13° (1913)
- Heating degree days
- 394
- Cooling degree days
- 0
San Tan Valley in February
Highs average 71°22° and lows 40°4°, with 1 in26 mm of precipitation in a typical February.
- Record high
- 93°34° (1940)
- Record low
- 11°−12° (1975)
- Heating degree days
- 269
- Cooling degree days
- 3
San Tan Valley in March
Highs average 78°26° and lows 45°7°, with 0.94 in24 mm of precipitation in a typical March.
- Record high
- 106°41° (2026)
- Record low
- 21°−6° (1971)
- Heating degree days
- 143
- Cooling degree days
- 40
San Tan Valley in April
Highs average 86°30° and lows 51°10°, with 0.25 in6.4 mm of precipitation in a typical April.
- Record high
- 106°41° (1943)
- Record low
- 25°−4° (1945)
- Heating degree days
- 41
- Cooling degree days
- 149
San Tan Valley in May
Highs average 95°35° and lows 59°15°, with 0.2 in5.1 mm of precipitation in a typical May.
- Record high
- 116°47° (1951)
- Record low
- 32°0° (1967)
- Heating degree days
- 4
- Cooling degree days
- 382
San Tan Valley in June
Highs average 105°41° and lows 68°20°, with 0.06 in1.5 mm of precipitation in a typical June.
- Record high
- 123°51° (1994)
- Record low
- 44°7° (1950)
- Heating degree days
- 0
- Cooling degree days
- 646
San Tan Valley in July
Highs average 107°41° and lows 77°25°, with 1.1 in28 mm of precipitation in a typical July.
- Record high
- 123°51° (1995)
- Record low
- 51°11° (1956)
- Heating degree days
- 0
- Cooling degree days
- 832
San Tan Valley in August
Highs average 105°41° and lows 77°25°, with 1.2 in31 mm of precipitation in a typical August.
- Record high
- 120°49° (1995)
- Record low
- 55°13° (1968)
- Heating degree days
- 0
- Cooling degree days
- 798
San Tan Valley in September
Highs average 101°38° and lows 70°21°, with 0.7 in18 mm of precipitation in a typical September.
- Record high
- 117°47° (2024)
- Record low
- 37°3° (1993)
- Heating degree days
- 0
- Cooling degree days
- 607
San Tan Valley in OctoberThis month
Highs average 91°33° and lows 56°13°, with 0.48 in12 mm of precipitation in a typical October.
- Record high
- 111°44° (1980)
- Record low
- 25°−4° (1971)
- Heating degree days
- 18
- Cooling degree days
- 278
San Tan Valley in November
Highs average 78°25° and lows 44°7°, with 0.49 in12 mm of precipitation in a typical November.
- Record high
- 97°36° (1965)
- Record low
- 17°−8° (1956)
- Heating degree days
- 167
- Cooling degree days
- 40
San Tan Valley in December
Highs average 67°19° and lows 36°2°, with 0.77 in20 mm of precipitation in a typical December.
- Record high
- 89°32° (1939)
- Record low
- 14°−10° (1953)
- Heating degree days
- 416
- Cooling degree days
- 0