St. Johns weather by month
What a typical year looks like in St. Johns, Arizona: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Saint Johns, 3 km from St. Johns; records cover 1901–2026.
The year at a glance
- Precipitation a year
- 9.4 in238 mm
- Snow a year
- 6 in16 cm
- Last spring freeze
- May 4
- First fall freeze
- Oct 12
- Heating degree days
- 4,638
- Cooling degree days
- 889
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are 7°−14° (heating, 99%) and 98°37° (cooling, 1%).
Month by month
St. Johns in January
Highs average 50°10° and lows 21°−6°, with 0.58 in15 mm of precipitation and 1.2 in3 cm of snow in a typical January.
- Record high
- 73°23° (1950)
- Record low
- −29°−34° (1971)
- Heating degree days
- 927
- Cooling degree days
- 0
St. Johns in February
Highs average 56°13° and lows 24°−5°, with 0.56 in14 mm of precipitation and 0.7 in1.8 cm of snow in a typical February.
- Record high
- 79°26° (2026)
- Record low
- −13°−25° (1921)
- Heating degree days
- 704
- Cooling degree days
- 0
St. Johns in March
Highs average 64°18° and lows 29°−2°, with 0.28 in7.1 mm of precipitation and 0.2 in0.5 cm of snow in a typical March.
- Record high
- 92°33° (2026)
- Record low
- −7°−22° (1951)
- Heating degree days
- 581
- Cooling degree days
- 0
St. Johns in April
Highs average 71°22° and lows 35°2°, with 0.27 in6.9 mm of precipitation and 0.1 in0.3 cm of snow in a typical April.
- Record high
- 95°35° (1943)
- Record low
- 7°−14° (1945)
- Heating degree days
- 360
- Cooling degree days
- 2
St. Johns in May
Highs average 80°27° and lows 44°7°, with 0.39 in9.9 mm of precipitation and 0.1 in0.3 cm of snow in a typical May.
- Record high
- 99°37° (2000)
- Record low
- 17°−8° (2019)
- Heating degree days
- 132
- Cooling degree days
- 36
St. Johns in June
Highs average 90°32° and lows 52°11°, with 0.19 in4.8 mm of precipitation in a typical June.
- Record high
- 103°39° (1902)
- Record low
- 25°−4° (1950)
- Heating degree days
- 11
- Cooling degree days
- 196
St. Johns in July
Highs average 91°33° and lows 60°15°, with 1.9 in49 mm of precipitation in a typical July.
- Record high
- 104°40° (1922)
- Record low
- 38°3° (1913)
- Heating degree days
- 0
- Cooling degree days
- 319
St. Johns in August
Highs average 88°31° and lows 58°14°, with 2 in50 mm of precipitation in a typical August.
- Record high
- 104°40° (1902)
- Record low
- 38°3° (1944)
- Heating degree days
- 1
- Cooling degree days
- 242
St. Johns in September
Highs average 83°28° and lows 51°10°, with 1.1 in29 mm of precipitation in a typical September.
- Record high
- 99°37° (1924)
- Record low
- 23°−5° (1912)
- Heating degree days
- 37
- Cooling degree days
- 91
St. Johns in OctoberThis month
Highs average 73°23° and lows 38°3°, with 0.86 in22 mm of precipitation and 0.5 in1.3 cm of snow in a typical October.
- Record high
- 92°33° (1910)
- Record low
- 7°−14° (2019)
- Heating degree days
- 302
- Cooling degree days
- 3
St. Johns in November
Highs average 60°16° and lows 27°−3°, with 0.55 in14 mm of precipitation and 0.9 in2.3 cm of snow in a typical November.
- Record high
- 82°28° (1934)
- Record low
- −21°−29° (1931)
- Heating degree days
- 639
- Cooling degree days
- 0
St. Johns in December
Highs average 49°10° and lows 20°−7°, with 0.66 in17 mm of precipitation and 2.5 in6.4 cm of snow in a typical December.
- Record high
- 78°26° (1911)
- Record low
- −25°−32° (1990)
- Heating degree days
- 944
- Cooling degree days
- 0