Symerton weather by month
What a typical year looks like in Symerton, Illinois: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at JOLIET BRANDON ROAD LOCK/DAM, 20 km from Symerton; records cover 1975–2026.
The year at a glance
- Precipitation a year
- 38 in966 mm
- Snow a year
- 17 in43 cm
- Last spring freeze
- Apr 13
- First fall freeze
- Oct 19
- Heating degree days
- 6,172
- Cooling degree days
- 872
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are −5°−21° (heating, 99%) and 93°34° (cooling, 1%).
Month by month
Symerton in January
Highs average 31°0° and lows 17°−9°, with 2 in51 mm of precipitation and 5 in13 cm of snow in a typical January.
- Record high
- 65°18° (1997)
- Record low
- −26°−32° (1985)
- Heating degree days
- 1276
- Cooling degree days
- 0
Symerton in February
Highs average 35°2° and lows 20°−7°, with 1.8 in45 mm of precipitation and 6 in16 cm of snow in a typical February.
- Record high
- 73°23° (2000)
- Record low
- −20°−29° (1979)
- Heating degree days
- 1047
- Cooling degree days
- 0
Symerton in March
Highs average 47°8° and lows 29°−2°, with 2.3 in58 mm of precipitation and 2.1 in5.3 cm of snow in a typical March.
- Record high
- 86°30° (1986)
- Record low
- −7°−22° (2002)
- Heating degree days
- 835
- Cooling degree days
- 1
Symerton in April
Highs average 60°16° and lows 39°4°, with 3.9 in100 mm of precipitation and 0.1 in0.3 cm of snow in a typical April.
- Record high
- 92°33° (1986)
- Record low
- 11°−12° (1982)
- Heating degree days
- 473
- Cooling degree days
- 5
Symerton in May
Highs average 71°22° and lows 49°10°, with 4.5 in115 mm of precipitation in a typical May.
- Record high
- 95°35° (2012)
- Record low
- 28°−2° (2020)
- Heating degree days
- 203
- Cooling degree days
- 54
Symerton in June
Highs average 80°27° and lows 60°16°, with 4.3 in109 mm of precipitation in a typical June.
- Record high
- 104°40° (1988)
- Record low
- 35°2° (1985)
- Heating degree days
- 30
- Cooling degree days
- 182
Symerton in July
Highs average 84°29° and lows 64°18°, with 4.6 in116 mm of precipitation in a typical July.
- Record high
- 103°39° (1995)
- Record low
- 47°8° (1983)
- Heating degree days
- 3
- Cooling degree days
- 278
Symerton in August
Highs average 82°28° and lows 63°17°, with 4 in101 mm of precipitation in a typical August.
- Record high
- 102°39° (1988)
- Record low
- 39°4° (1986)
- Heating degree days
- 6
- Cooling degree days
- 234
Symerton in September
Highs average 76°25° and lows 55°13°, with 3.2 in81 mm of precipitation in a typical September.
- Record high
- 97°36° (1978)
- Record low
- 32°0° (1983)
- Heating degree days
- 83
- Cooling degree days
- 105
Symerton in OctoberThis month
Highs average 63°17° and lows 43°6°, with 3.1 in80 mm of precipitation in a typical October.
- Record high
- 88°31° (2005)
- Record low
- 17°−8° (1976)
- Heating degree days
- 374
- Cooling degree days
- 13
Symerton in November
Highs average 49°9° and lows 32°0°, with 2.5 in62 mm of precipitation and 0.3 in0.8 cm of snow in a typical November.
- Record high
- 78°26° (1975)
- Record low
- −2°−19° (1977)
- Heating degree days
- 738
- Cooling degree days
- 0
Symerton in December
Highs average 36°2° and lows 22°−5°, with 1.9 in49 mm of precipitation and 3 in8 cm of snow in a typical December.
- Record high
- 70°21° (1982)
- Record low
- −20°−29° (1983)
- Heating degree days
- 1104
- Cooling degree days
- 0