Geneseo weather by month
What a typical year looks like in Geneseo, Illinois: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Geneseo, 1 km from Geneseo; records cover 1895–2026.
The year at a glance
- Precipitation a year
- 39.1 in993 mm
- Snow a year
- 28 in72 cm
- Last spring freeze
- Apr 13
- First fall freeze
- Oct 17
- Heating degree days
- 6,140
- Cooling degree days
- 1,032
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 95°35° (cooling, 1%).
Month by month
Geneseo in January
Highs average 31°−1° and lows 15°−10°, with 1.6 in42 mm of precipitation and 10 in25 cm of snow in a typical January.
- Record high
- 66°19° (1944)
- Record low
- −25°−32° (2019)
- Heating degree days
- 1311
- Cooling degree days
- 0
Geneseo in February
Highs average 36°2° and lows 19°−7°, with 1.8 in46 mm of precipitation and 6 in15 cm of snow in a typical February.
- Record high
- 76°24° (2024)
- Record low
- −25°−32° (1905)
- Heating degree days
- 1060
- Cooling degree days
- 0
Geneseo in March
Highs average 49°9° and lows 29°−1°, with 2.7 in69 mm of precipitation and 2.8 in7.1 cm of snow in a typical March.
- Record high
- 89°32° (1945)
- Record low
- −13°−25° (1943)
- Heating degree days
- 805
- Cooling degree days
- 2
Geneseo in April
Highs average 62°17° and lows 40°4°, with 4 in101 mm of precipitation and 0.7 in1.8 cm of snow in a typical April.
- Record high
- 92°33° (1986)
- Record low
- 12°−11° (1982)
- Heating degree days
- 428
- Cooling degree days
- 10
Geneseo in May
Highs average 74°23° and lows 52°11°, with 4.9 in124 mm of precipitation in a typical May.
- Record high
- 99°37° (2018)
- Record low
- 26°−3° (1966)
- Heating degree days
- 152
- Cooling degree days
- 79
Geneseo in June
Highs average 83°28° and lows 62°16°, with 4.4 in112 mm of precipitation in a typical June.
- Record high
- 101°38° (1971)
- Record low
- 37°3° (1945)
- Heating degree days
- 16
- Cooling degree days
- 231
Geneseo in July
Highs average 86°30° and lows 65°18°, with 4.1 in105 mm of precipitation in a typical July.
- Record high
- 107°42° (1901)
- Record low
- 44°7° (1947)
- Heating degree days
- 2
- Cooling degree days
- 324
Geneseo in August
Highs average 83°29° and lows 63°17°, with 4.1 in104 mm of precipitation in a typical August.
- Record high
- 103°39° (1988)
- Record low
- 40°4° (1986)
- Heating degree days
- 5
- Cooling degree days
- 258
Geneseo in September
Highs average 77°25° and lows 55°13°, with 3.6 in91 mm of precipitation in a typical September.
- Record high
- 99°37° (1971)
- Record low
- 24°−4° (1942)
- Heating degree days
- 87
- Cooling degree days
- 111
Geneseo in OctoberThis month
Highs average 64°18° and lows 43°6°, with 3.2 in82 mm of precipitation and 0.1 in0.3 cm of snow in a typical October.
- Record high
- 92°33° (1997)
- Record low
- 19°−7° (1942)
- Heating degree days
- 375
- Cooling degree days
- 17
Geneseo in November
Highs average 49°9° and lows 31°−1°, with 2.6 in65 mm of precipitation and 1.6 in4.1 cm of snow in a typical November.
- Record high
- 79°26° (2000)
- Record low
- −7°−22° (1976)
- Heating degree days
- 758
- Cooling degree days
- 0
Geneseo in December
Highs average 36°2° and lows 21°−6°, with 2.1 in54 mm of precipitation and 7 in19 cm of snow in a typical December.
- Record high
- 70°21° (1998)
- Record low
- −20°−29° (1983)
- Heating degree days
- 1141
- Cooling degree days
- 0