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Key findings

  • The highest monthly average temperature in Ottawa for July is 75.2 degrees
  • The lowest monthly average temperature in Ottawa for January is 25.7 degrees
  • The most monthly precipitation in Ottawa occurs in August with 8.2 inches
  • The air quality index in Ottawa is 100% better than the national average
  • The pollution index in Ottawa is 63% better than the national average

Compare Ottawa, IL Weather

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      Ottawa 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
      January18°F34°F26°F3.3"
      February19°F35°F26°F3.0"
      March32°F51°F40°F4.3"
      April42°F64°F52°F7.2"
      May53°F75°F63°F8.0"
      June62°F83°F72°F7.5"
      July66°F85°F75°F7.1"
      August64°F83°F73°F8.2"
      September56°F78°F66°F6.3"
      October45°F65°F54°F6.6"
      November34°F51°F42°F4.3"
      December23°F37°F30°F3.5"

      Ottawa 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.
      IndexOttawaIllinoisNational
      Air quality index04150
      Pollution index1,874,4903,347,2955,066,862

      Ottawa air quality information

      MeasurementTotal
      Days measured335
      Days with good air quality334
      Days with moderate air quality1
      Days w/ poor A.Q. for sensitive groups0
      Days with unhealthy air quality0

      Ottawa air quality information

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

      Average monthly Ottawa temperature with heat index

      Ottawa monthly precipitation with daily maximum

      Ottawa monthly snow depth with daily maximum

      Ottawa monthly wind speed information

      Nearby cities with good air quality

      City, StatePopulationAir Quality IndexNational Avg.
      Troy Grove, IL2810100%
      LaSalle, IL9,4840100%
      Kinsman, IL850100%
      Oglesby, IL3,8340100%
      Mendota, IL7,1820100%
      Ottawa, IL18,7070100%

      Cities with similar population

      City, StatePopulationAir Quality IndexNational Avg.
      Middleton, WI18,7073922%
      Thomasville, GA18,7064020%
      South Burlington, VT18,7043726%
      Fairmont, WV18,6993138%
      Augusta, ME18,6912844%
      Ottawa, IL18,7070100%
      Source: The Ottawa, 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.