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Key findings

  • The highest monthly average temperature in DeKalb for July is 72.2 degrees
  • The lowest monthly average temperature in DeKalb for January is 22.8 degrees
  • The most monthly precipitation in DeKalb occurs in August with 5.9 inches
  • The air quality index in DeKalb is 16% better than the national average
  • The pollution index in DeKalb is 63% better than the national average

Compare DeKalb, IL Weather

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      DeKalb Average Temperature

      In the event that the weather data was unavailable for this city, estimates based upon nearby cities were used.
      MonthTemp. (min)Temp. (max)Temp. (avg)Precipitation
      January16°F31°F23°F2.8"
      February17°F32°F24°F2.8"
      March30°F47°F37°F4.6"
      April39°F61°F49°F5.8"
      May50°F72°F60°F5.3"
      June59°F80°F69°F5.6"
      July63°F82°F72°F5.8"
      August61°F81°F70°F5.9"
      September54°F75°F63°F3.7"
      October43°F63°F52°F5.8"
      November32°F49°F39°F4.0"
      December21°F34°F27°F3.1"

      DeKalb air quality index & pollution index

      In the event that the air quality/pollution data was unavailable for this city, estimates based upon nearby cities were used.
      IndexDeKalbIllinoisNational
      Air quality index424150
      Pollution index1,874,4903,347,2955,066,862

      DeKalb air quality information

      MeasurementTotal
      Days measured341
      Days with good air quality240
      Days with moderate air quality100
      Days w/ poor A.Q. for sensitive groups1
      Days with unhealthy air quality0

      DeKalb air quality information

      PollutantTotal
      Arsenic0.002%
      Benzene0.030%
      Carbon Tetrachloride0.010%
      Lead0.010%
      Mercury0.010%

      Average monthly DeKalb temperature with heat index

      DeKalb monthly precipitation with daily maximum

      DeKalb monthly snow depth with daily maximum

      DeKalb monthly wind speed information

      Nearby cities with good air quality

      City, StatePopulationAir Quality IndexNational Avg.
      Big Rock, IL1,1390100%
      Waterman, IL1,5270100%
      Kaneville, IL4210100%
      Hinckley, IL2,0530100%
      Lee, IL3580100%
      DeKalb, IL43,2694216%

      Cities with similar population

      City, StatePopulationAir Quality IndexNational Avg.
      Cleveland, TN43,276198%
      Freeport, NY43,217512%
      West Babylon, NY43,359512%
      Annandale, VA43,158476%
      Bothell, WA43,1534510%
      DeKalb, IL43,2694216%
      Source: The DeKalb, IL weather data displayed above is derived from the NOAA (National Oceanic and Atmospheric). Air quality and pollution data is derived from the EPA (United States Environmental Protection Agency). Air quality and pollution levels measured in a particular area may not be representative of the entire county.