St. Clair weather by month
What a typical year looks like in St. Clair, Michigan: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at PORT HURON, 18 km from St. Clair; records cover 1931–2026.
The year at a glance
- Precipitation a year
- 34.9 in886 mm
- Snow a year
- 36 in90 cm
- Last spring freeze
- Apr 23
- First fall freeze
- Nov 3
- Heating degree days
- 6,343
- Cooling degree days
- 749
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are 1°−17° (heating, 99%) and 93°34° (cooling, 1%).
Month by month
St. Clair in January
Highs average 31°−1° and lows 20°−7°, with 2.5 in63 mm of precipitation and 11 in28 cm of snow in a typical January.
- Record high
- 64°18° (1950)
- Record low
- −19°−28° (1994)
- Heating degree days
- 1227
- Cooling degree days
- 0
St. Clair in February
Highs average 33°1° and lows 21°−6°, with 2.1 in52 mm of precipitation and 11 in29 cm of snow in a typical February.
- Record high
- 69°21° (2000)
- Record low
- −15°−26° (1934)
- Heating degree days
- 1067
- Cooling degree days
- 0
St. Clair in March
Highs average 42°6° and lows 28°−2°, with 2.2 in56 mm of precipitation and 5 in12 cm of snow in a typical March.
- Record high
- 82°28° (2012)
- Record low
- −7°−22° (2003)
- Heating degree days
- 922
- Cooling degree days
- 0
St. Clair in April
Highs average 54°12° and lows 38°3°, with 3.2 in80 mm of precipitation and 0.4 in1 cm of snow in a typical April.
- Record high
- 87°31° (1941)
- Record low
- 8°−13° (1954)
- Heating degree days
- 569
- Cooling degree days
- 2
St. Clair in May
Highs average 67°19° and lows 49°9°, with 3.5 in90 mm of precipitation in a typical May.
- Record high
- 96°36° (2006)
- Record low
- 21°−6° (1941)
- Heating degree days
- 260
- Cooling degree days
- 35
St. Clair in June
Highs average 76°25° and lows 59°15°, with 3.6 in92 mm of precipitation in a typical June.
- Record high
- 102°39° (1988)
- Record low
- 32°0° (1945)
- Heating degree days
- 56
- Cooling degree days
- 134
St. Clair in July
Highs average 81°27° and lows 65°18°, with 3.3 in83 mm of precipitation in a typical July.
- Record high
- 103°39° (1936)
- Record low
- 35°2° (1936)
- Heating degree days
- 5
- Cooling degree days
- 260
St. Clair in August
Highs average 80°27° and lows 64°18°, with 3.1 in80 mm of precipitation in a typical August.
- Record high
- 102°39° (1955)
- Record low
- 37°3° (1942)
- Heating degree days
- 8
- Cooling degree days
- 220
St. Clair in September
Highs average 73°23° and lows 57°14°, with 3.3 in84 mm of precipitation in a typical September.
- Record high
- 101°38° (1953)
- Record low
- 25°−4° (1942)
- Heating degree days
- 89
- Cooling degree days
- 88
St. Clair in OctoberThis month
Highs average 61°16° and lows 46°8°, with 3.1 in80 mm of precipitation in a typical October.
- Record high
- 90°32° (1951)
- Record low
- 20°−7° (1976)
- Heating degree days
- 374
- Cooling degree days
- 10
St. Clair in November
Highs average 47°8° and lows 35°2°, with 2.8 in71 mm of precipitation and 1.3 in3.3 cm of snow in a typical November.
- Record high
- 81°27° (1950)
- Record low
- 2°−17° (1950)
- Heating degree days
- 718
- Cooling degree days
- 0
St. Clair in December
Highs average 36°2° and lows 26°−3°, with 2.2 in55 mm of precipitation and 7 in17 cm of snow in a typical December.
- Record high
- 66°19° (1998)
- Record low
- −7°−22° (1983)
- Heating degree days
- 1048
- Cooling degree days
- 0