Sullivan Illinois Climate Data

Monthly Average Climate Data for Sullivan Illinois

Switch Data to Celsius/Metric Units
MonthAvg. LowAvg. HighAvg. Precip
January19.3 °F35.3 °F2.38 in.
February22.4 °F40.1 °F2.18 in.
March31.5 °F51.2 °F2.91 in.
April42.1 °F64.1 °F4.49 in.
May53.6 °F74.4 °F4.79 in.
June62.4 °F83.1 °F4.7 in.
July65.4 °F86.0 °F4.04 in.
August63.0 °F84.7 °F2.87 in.
September55.3 °F79.8 °F3.0 in.
October44.0 °F67.3 °F3.36 in.
November33.2 °F52.1 °F3.31 in.
December25.1 °F40.1 °F2.53 in.
Annual43.1 °F63.2 °F40.56 in.

Climate Data for Sullivan Illinois

Average First Frost DateOct. 11 - Oct. 20
Average Last Frost DateApr. 11 - Apr. 20
Average Days With Frost100-125 Days
Plant Hardiness Zone - 2023Zone 6a : -10°F to -5°F
Plant Hardiness Zone - 2012Zone 6a : -10°F to -5°F
Current Drought ConditionsAbnormally Dry
Köppen Climate ClassificationDfa - Humid Continental Hot Summers With Year Around Precipitation
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