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United States › Illinois › DeKalb County › Climate Station DE KALB, IL US Distance 2.8 mi Normals 1991–2020

30-year climate normals

DeKalb County Climate and Weather Averages

Hottest month — July

83.1°

average daily high. The coldest month is January, averaging a low of 13.1°F.

DeKalb County gets 37.25" of precipitation a year and 33.1" of snow, and 36% of it falls in May, Jun, Jul.

Temperature through the year

Each bar spans the average daily low to the average daily high for that month.

20° 40° 60° 80° JanFebMarAprMayJunJulAugSepOctNovDec
MonthAvg highAvg low PrecipSnow
January 28.1° 13.1° 1.69" 10.2"
February 32.5° 16.6° 1.71" 8.7"
March 45.0° 26.8° 2.24" 4.4"
April 58.6° 37.3° 3.56" 1.3"
May 70.2° 49.2° 4.79" 0.0"
June 79.9° 59.5° 4.57" 0.0"
July 83.1° 63.3° 4.00" 0.0"
August 81.2° 61.3° 4.06" 0.0"
September 74.9° 53.2° 3.32" 0.0"
October 62.0° 41.0° 2.96" 0.1"
November 46.3° 29.6° 2.31" 1.8"
December 33.6° 19.1° 2.04" 6.6"

Rainfall by month

Precipitation is spread fairly evenly through the year here, with 36% falling in the wettest three months (May, Jun, Jul).

January 1.69"
February 1.71"
March 2.24"
April 3.56"
May 4.79"
June 4.57"
July 4.00"
August 4.06"
September 3.32"
October 2.96"
November 2.31"
December 2.04"
Annual total 37.25"

What this climate costs you

Degree days measure how hard a building has to work to stay comfortable. They are the reason two identical houses have very different power bills, and they are the link between the weather here and what you pay every month.

Cooling degree days How much air conditioning the climate demands 790
Heating degree days How much heating the climate demands 6,745
Approximate annual cooling cost At 23.85¢/kWh, Illinois average $188
Approximate annual electric heating cost Lower where heating is gas rather than electric $563

These are rough planning figures from degree days and the state electricity price, not a bill estimate. House size, insulation and fuel type move them a lot. See the full cost of owning a home in DeKalb County, where electricity is one line of eight.

Common questions

What is the weather like in DeKalb County?

DeKalb County averages a high of 83.1°F in July and a low of 13.1°F in January. Annual precipitation is 37.25 inches, including 33.1 inches of snow.

When is the rainy season in DeKalb County?

The wettest stretch is May, Jun, Jul, which accounts for 36% of the year's precipitation. Precipitation is relatively evenly distributed across the year.

How hot does it get in DeKalb County?

The average daily high in July, the hottest month, is 83.1°F. That drives 790 cooling degree days a year, which is what your air conditioning has to work against.

Does it snow in DeKalb County?

Yes. DeKalb County averages 33.1 inches of snow a year.

Sources

  • Temperature, precipitation and snowfall normals — NOAA National Centers for Environmental Information, 1991–2020 Monthly Climate Normals, station DE KALB, IL US (USC00112223), 2.8 miles from the county centroid.
  • Heating and cooling degree days — NOAA, same station and period.
  • Electricity price — US Energy Information Administration, Electric Power Monthly Table 5.6.A, Illinois residential average.
  • Wet-season share is the wettest three consecutive months as a percentage of annual precipitation, calculated from the monthly normals.