Westchester Illinois Climate Data

Monthly Average Climate Data for Westchester Illinois

Switch Data to Celsius/Metric Units
MonthAvg. LowAvg. HighAvg. Precip
January17.2 °F31.8 °F2.17 in.
February19.9 °F35.6 °F2.13 in.
March29.2 °F46.4 °F2.36 in.
April39.6 °F59.2 °F3.97 in.
May50.5 °F70.4 °F4.74 in.
June60.6 °F80.5 °F4.39 in.
July65.7 °F84.8 °F3.99 in.
August64.2 °F82.8 °F4.18 in.
September56.3 °F76.2 °F3.34 in.
October44.1 °F63.1 °F3.49 in.
November32.8 °F49.0 °F2.57 in.
December22.9 °F37.0 °F2.31 in.
Annual41.9 °F59.7 °F39.64 in.

Climate Data for Westchester Illinois

Average First Frost DateOct. 21 - Oct. 31
Average Last Frost DateMay 1 - May 10
Average Days With Frost100-125 Days
Plant Hardiness Zone - 2023Zone 6a : -10°F to -5°F
Plant Hardiness Zone - 2012Zone 5b : -15°F to -10°F
Current Drought ConditionsModerate Drought
Köppen Climate ClassificationDfa - Humid Continental Hot Summers With Year Around Precipitation
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