Is this weather normal in Boone County?

Illinois · county records since 1895, through September 2026.

Weather › Illinois › Boone County

Boone County's warmest year in 131 on record was 2024, at 52.0° on average. Boone County has warmed about 0.5° per decade since 1970.

This week

Usual for Oct 28 to Nov 3: highs near 54°, lows near 35°

That is the 1991 to 2020 average for these dates in Boone County. The Weather Service forecast fills in below.

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usual high for the datewarmercooler

The last 12 months

Oct: +5.0°OctNov: +1.2°NovDec: -3.2°DecJan 2026: -2.5°JanFeb: +5.3°FebMar: +5.3°MarApr: +5.3°AprMay: 0.0°MayJun: -0.3°JunJul: +2.3°JulAug: +0.3°AugSep: +3.8°Sepwarmercooler

Each bar is a month's average temperature against the usual for that month (1991 to 2020). Ranks compare the same month in every year since 1895.

Every year since 1895

18952025

Rain and drought

Oct: -1.4 inOctNov: -0.6 inNovDec: -0.1 inDecJan 2026: -0.5 inJanFeb: -1.3 inFebMar: +1.3 inMarApr: +4.9 inAprMay: -3.6 inMayJun: +1.8 inJunJul: -2.1 inJulAug: +0.7 inAugSep: +2.1 inSepwetterdrier

Rain and melted snow against the usual for each month. The drought reading is NOAA's Palmer index for the county.

Month by month in Boone County

MonthUsual high / lowUsual rainWarmestColdest
January29° / 13°1.6 in32.8° 20064.3° 1912
February33° / 17°1.6 in36.5° 19987.6° 1936
March45° / 27°2.2 in50.8° 201221.7° 1960
April59° / 37°3.7 in55.2° 191538.9° 2018
May70° / 48°4.4 in66.4° 197751.2° 1907
June80° / 58°5.1 in75.7° 193362.3° 1916
July83° / 62°3.9 in79.6° 190166.2° 2009
August81° / 60°4.0 in77.9° 194763.8° 1915
September75° / 52°3.5 in68.9° 189756.9° 1924
October62° / 40°2.9 in60.3° 196339.9° 1925
November46° / 30°2.4 in47.5° 200128.1° 1951
December34° / 19°1.9 in36.8° 201511.9° 1983

Warmest and coldest are the month's whole-month average temperature, with the year it happened.

Towns in Boone County

Crime Radar: Loves Park, Belvidere, Cherry Valley

Nearby counties