Lake St. Clair weather by month
What a typical year looks like in Lake St. Clair, Missouri: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Washington, 24 km from Lake St. Clair; records cover 2009–2026.
The year at a glance
- Precipitation a year
- 44.1 in1120 mm
- Snow a year
- 8 in20 cm
- Last spring freeze
- Apr 13
- First fall freeze
- Oct 21
- Heating degree days
- 4,965
- Cooling degree days
- 1,298
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are 2°−17° (heating, 99%) and 97°36° (cooling, 1%).
Month by month
Lake St. Clair in January
Highs average 40°4° and lows 20°−7°, with 2.5 in64 mm of precipitation and 2.6 in6.6 cm of snow in a typical January.
- Record high
- 73°23° (2013)
- Record low
- −21°−29° (2014)
- Heating degree days
- 1083
- Cooling degree days
- 0
Lake St. Clair in February
Highs average 45°7° and lows 23°−5°, with 2.5 in64 mm of precipitation and 1.4 in3.6 cm of snow in a typical February.
- Record high
- 84°29° (2024)
- Record low
- −11°−24° (2014)
- Heating degree days
- 857
- Cooling degree days
- 0
Lake St. Clair in March
Highs average 56°13° and lows 32°0°, with 3.7 in93 mm of precipitation and 0.7 in1.8 cm of snow in a typical March.
- Record high
- 94°34° (2026)
- Record low
- 1°−17° (2014)
- Heating degree days
- 655
- Cooling degree days
- 3
Lake St. Clair in April
Highs average 67°20° and lows 43°6°, with 4.6 in116 mm of precipitation and 0.1 in0.3 cm of snow in a typical April.
- Record high
- 91°33° (2010)
- Record low
- 24°−4° (2018)
- Heating degree days
- 315
- Cooling degree days
- 17
Lake St. Clair in May
Highs average 76°24° and lows 54°12°, with 5.3 in135 mm of precipitation in a typical May.
- Record high
- 95°35° (2018)
- Record low
- 34°1° (2011)
- Heating degree days
- 107
- Cooling degree days
- 107
Lake St. Clair in June
Highs average 84°29° and lows 64°18°, with 4.2 in107 mm of precipitation in a typical June.
- Record high
- 107°42° (2012)
- Record low
- 46°8° (2012)
- Heating degree days
- 6
- Cooling degree days
- 266
Lake St. Clair in July
Highs average 88°31° and lows 67°19°, with 4.2 in106 mm of precipitation in a typical July.
- Record high
- 105°41° (2012)
- Record low
- 51°11° (2013)
- Heating degree days
- 0
- Cooling degree days
- 392
Lake St. Clair in August
Highs average 87°31° and lows 65°18°, with 3.8 in95 mm of precipitation in a typical August.
- Record high
- 103°39° (2011)
- Record low
- 48°9° (2025)
- Heating degree days
- 2
- Cooling degree days
- 339
Lake St. Clair in September
Highs average 80°26° and lows 56°13°, with 3.7 in94 mm of precipitation in a typical September.
- Record high
- 101°38° (2026)
- Record low
- 36°2° (2012)
- Heating degree days
- 62
- Cooling degree days
- 143
Lake St. Clair in OctoberThis month
Highs average 69°21° and lows 44°6°, with 3.4 in86 mm of precipitation in a typical October.
- Record high
- 92°33° (2019)
- Record low
- 23°−5° (2013)
- Heating degree days
- 300
- Cooling degree days
- 29
Lake St. Clair in November
Highs average 55°13° and lows 33°0°, with 3.7 in93 mm of precipitation and 0.4 in1 cm of snow in a typical November.
- Record high
- 86°30° (2023)
- Record low
- 10°−12° (2019)
- Heating degree days
- 630
- Cooling degree days
- 2
Lake St. Clair in December
Highs average 45°7° and lows 24°−4°, with 2.6 in67 mm of precipitation and 2.7 in6.9 cm of snow in a typical December.
- Record high
- 78°26° (2025)
- Record low
- −7°−22° (2022)
- Heating degree days
- 948
- Cooling degree days
- 0