TODAY MAY12
TEMPERATURE
HUMIDITY
PRESSURE
WIND COND.
  • 6742Thu
  • 6848Fri
  • 6752Sat
  • 6855Sun
  • 7254Mon
daynightWeather update from De Kalb Taylor Municipal Airport at

Key findings

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

Compare Cortland, IL Weather

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      Cortland 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"

      Cortland 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.
      IndexCortlandIllinoisNational
      Air quality index424150
      Pollution index1,874,4903,347,2955,066,862

      Cortland 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

      Cortland air quality information

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

      Average monthly Cortland temperature with heat index

      Cortland monthly precipitation with daily maximum

      Cortland monthly snow depth with daily maximum

      Cortland monthly wind speed information

      Nearby cities with good air quality

      City, StatePopulationAir Quality IndexNational Avg.
      Sugar Grove, IL9,2880100%
      Shabbona, IL9820100%
      Kaneville, IL4210100%
      Big Rock, IL1,1390100%
      Waterman, IL1,5270100%
      Cortland, IL4,1354216%

      Cities with similar population

      City, StatePopulationAir Quality IndexNational Avg.
      Wolfforth, TX4,1352550%
      Grant, MN4,134468%
      Eldorado, IL4,1344314%
      Wayland, MI4,1343922%
      Butler, MO4,138476%
      Cortland, IL4,1354216%
      Source: The Cortland, 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.