Olney weather by month
What a typical year looks like in Olney, Illinois: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Olney 2s, 3 km from Olney; records cover 1896–2026.
The year at a glance
- Precipitation a year
- 48.8 in1239 mm
- Snow a year
- 11 in27 cm
- Last spring freeze
- Apr 9
- First fall freeze
- Oct 19
- Heating degree days
- 5,100
- Cooling degree days
- 1,196
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 95°35° (cooling, 1%).
Month by month
Olney in January
Highs average 38°3° and lows 21°−6°, with 3.5 in89 mm of precipitation and 4 in9 cm of snow in a typical January.
- Record high
- 75°24° (1943)
- Record low
- −24°−31° (1994)
- Heating degree days
- 1106
- Cooling degree days
- 0
Olney in February
Highs average 43°6° and lows 24°−5°, with 2.6 in65 mm of precipitation and 2.6 in6.6 cm of snow in a typical February.
- Record high
- 78°26° (1972)
- Record low
- −25°−32° (1951)
- Heating degree days
- 888
- Cooling degree days
- 0
Olney in March
Highs average 53°12° and lows 32°0°, with 4.2 in107 mm of precipitation and 1.1 in2.8 cm of snow in a typical March.
- Record high
- 89°32° (1910)
- Record low
- −15°−26° (1978)
- Heating degree days
- 690
- Cooling degree days
- 3
Olney in April
Highs average 66°19° and lows 43°6°, with 5 in128 mm of precipitation in a typical April.
- Record high
- 91°33° (1930)
- Record low
- 21°−6° (1944)
- Heating degree days
- 340
- Cooling degree days
- 15
Olney in May
Highs average 75°24° and lows 53°12°, with 5.6 in142 mm of precipitation in a typical May.
- Record high
- 98°37° (1911)
- Record low
- 29°−2° (1963)
- Heating degree days
- 116
- Cooling degree days
- 92
Olney in June
Highs average 84°29° and lows 62°17°, with 4.8 in122 mm of precipitation in a typical June.
- Record high
- 106°41° (1931)
- Record low
- 36°2° (1917)
- Heating degree days
- 10
- Cooling degree days
- 257
Olney in July
Highs average 87°30° and lows 66°19°, with 5 in126 mm of precipitation in a typical July.
- Record high
- 112°44° (1936)
- Record low
- 45°7° (1937)
- Heating degree days
- 0
- Cooling degree days
- 348
Olney in August
Highs average 86°30° and lows 64°18°, with 3.2 in81 mm of precipitation in a typical August.
- Record high
- 109°43° (1930)
- Record low
- 41°5° (1915)
- Heating degree days
- 2
- Cooling degree days
- 305
Olney in September
Highs average 80°27° and lows 56°13°, with 3.3 in84 mm of precipitation in a typical September.
- Record high
- 106°41° (1925)
- Record low
- 27°−3° (1899)
- Heating degree days
- 53
- Cooling degree days
- 146
Olney in OctoberThis month
Highs average 69°20° and lows 44°7°, with 3.8 in97 mm of precipitation in a typical October.
- Record high
- 97°36° (1953)
- Record low
- 17°−8° (1952)
- Heating degree days
- 294
- Cooling degree days
- 28
Olney in November
Highs average 54°12° and lows 34°1°, with 4.3 in108 mm of precipitation and 0.5 in1.3 cm of snow in a typical November.
- Record high
- 83°28° (1933)
- Record low
- −2°−19° (1929)
- Heating degree days
- 640
- Cooling degree days
- 2
Olney in December
Highs average 42°6° and lows 26°−4°, with 3.5 in89 mm of precipitation and 2.7 in6.9 cm of snow in a typical December.
- Record high
- 74°23° (1982)
- Record low
- −19°−28° (1989)
- Heating degree days
- 961
- Cooling degree days
- 0