Rosemont weather by month
What a typical year looks like in Rosemont, Illinois: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Chicago Ohare International Airport, 6 km from Rosemont; records cover 1872–2026.
The year at a glance
- Precipitation a year
- 37.9 in962 mm
- Snow a year
- 38 in98 cm
- Last spring freeze
- Apr 21
- First fall freeze
- Oct 16
- Heating degree days
- 5,974
- Cooling degree days
- 1,003
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are −3°−19° (heating, 99%) and 94°34° (cooling, 1%).
Month by month
Rosemont in January
Highs average 32°0° and lows 19°−7°, with 2 in51 mm of precipitation and 11 in29 cm of snow in a typical January.
- Record high
- 67°19° (1950)
- Record low
- −27°−33° (1985)
- Heating degree days
- 1234
- Cooling degree days
- 0
Rosemont in February
Highs average 36°2° and lows 22°−6°, with 2 in50 mm of precipitation and 11 in27 cm of snow in a typical February.
- Record high
- 75°24° (1976)
- Record low
- −21°−29° (1899)
- Heating degree days
- 1015
- Cooling degree days
- 0
Rosemont in March
Highs average 47°8° and lows 31°−1°, with 2.5 in62 mm of precipitation and 6 in14 cm of snow in a typical March.
- Record high
- 88°31° (1986)
- Record low
- −12°−24° (1873)
- Heating degree days
- 808
- Cooling degree days
- 2
Rosemont in April
Highs average 59°15° and lows 40°5°, with 3.8 in95 mm of precipitation and 1.3 in3.3 cm of snow in a typical April.
- Record high
- 91°33° (1942)
- Record low
- 7°−14° (1982)
- Heating degree days
- 468
- Cooling degree days
- 8
Rosemont in May
Highs average 71°21° and lows 51°10°, with 4.5 in114 mm of precipitation in a typical May.
- Record high
- 98°37° (1934)
- Record low
- 27°−3° (1875)
- Heating degree days
- 198
- Cooling degree days
- 60
Rosemont in June
Highs average 80°27° and lows 61°16°, with 4.1 in104 mm of precipitation in a typical June.
- Record high
- 104°40° (1953)
- Record low
- 35°2° (1945)
- Heating degree days
- 31
- Cooling degree days
- 199
Rosemont in July
Highs average 85°29° and lows 66°19°, with 3.7 in94 mm of precipitation in a typical July.
- Record high
- 105°41° (1934)
- Record low
- 45°7° (1983)
- Heating degree days
- 2
- Cooling degree days
- 326
Rosemont in August
Highs average 83°28° and lows 65°18°, with 4.3 in108 mm of precipitation in a typical August.
- Record high
- 102°39° (1918)
- Record low
- 42°6° (1986)
- Heating degree days
- 4
- Cooling degree days
- 277
Rosemont in September
Highs average 76°24° and lows 57°14°, with 3.2 in81 mm of precipitation in a typical September.
- Record high
- 101°38° (1953)
- Record low
- 29°−2° (1942)
- Heating degree days
- 77
- Cooling degree days
- 116
Rosemont in OctoberThis month
Highs average 63°17° and lows 45°7°, with 3.4 in87 mm of precipitation and 0.2 in0.5 cm of snow in a typical October.
- Record high
- 94°34° (1963)
- Record low
- 14°−10° (1887)
- Heating degree days
- 355
- Cooling degree days
- 15
Rosemont in November
Highs average 48°9° and lows 34°1°, with 2.4 in61 mm of precipitation and 1.8 in4.6 cm of snow in a typical November.
- Record high
- 81°27° (1950)
- Record low
- −2°−19° (1872)
- Heating degree days
- 713
- Cooling degree days
- 0
Rosemont in December
Highs average 37°3° and lows 24°−4°, with 2.1 in54 mm of precipitation and 8 in19 cm of snow in a typical December.
- Record high
- 71°22° (1970)
- Record low
- −25°−32° (1983)
- Heating degree days
- 1069
- Cooling degree days
- 0