TODAY NOV21
TEMPERATURE42
HUMIDITY85
PRESSURE101250
WIND COND.
  • 514470%
  • 5643Fri100%70%
  • 5143Sat80%80%
  • 5041Sun70%
  • 5039Mon
daynightWeather update from Renton Municipal Airport at
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Weather Quick Facts

  • The highest monthly average temperature in Mercer Island for August is 67.5 degrees
  • The lowest monthly average temperature in Mercer Island for December is 41.4 degrees
  • The most monthly precipitation in Mercer Island occurs in November with 6.6 inches
  • The air quality index in Mercer Island is 7% worse than the national average
  • The pollution index in Mercer Island is 60% better than the national average

Compare Mercer Island, WA Weather

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      Mercer Island 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
      January36°F49°F42°F5.1"
      February37°F52°F44°F3.8"
      March40°F55°F47°F4.9"
      April43°F61°F51°F3.1"
      May49°F68°F57°F2.2"
      June54°F72°F62°F1.5"
      July58°F79°F67°F0.4"
      August58°F79°F68°F0.6"
      September54°F73°F62°F1.6"
      October47°F62°F54°F3.9"
      November40°F53°F47°F6.6"
      December36°F48°F41°F6.1"

      Mercer Island 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.
      IndexMercer IslandWashingtonNational
      Air quality index453642
      Pollution index1,081,4304,541,8502,726,193

      Mercer Island air quality

      MeasurementTotal
      Days measured365
      Days with good air quality236
      Days with moderate air quality127
      Days w/ poor A.Q. for sensitive groups2
      Days with unhealthy air quality0

      Air quality details

      PollutantTotal
      Arsenic0.000%
      Benzene0.010%
      Carbon Tetrachloride0.000%
      Lead0.000%
      Mercury0.000%

      Average monthly Mercer Island temperature with heat index

      Mercer Island monthly precipitation with daily maximum

      Mercer Island monthly snow depth with daily maximum

      Mercer Island monthly wind speed information

      Nearby cities with good air quality

      CityPopulationAir Quality IndexNational Avg.
      Manchester, WA6,0501864.0%
      Southworth, WA2,3001864.0%
      Fairwood CDP (Spokane County), WA8,0554510.0%
      Covington, WA21,1314510.0%
      Issaquah, WA38,7074510.0%
      Mercer Island, WA25,8204510.0%

      Cities with similar population

      CityPopulationAir Quality IndexNational Avg.
      Kankakee, IL25,8185510.0%
      Mauldin, SC25,829468.0%
      Holbrook, NY25,7944314.0%
      Socastee, SC25,8461472.0%
      Lebanon, PA25,7794216.0%
      Mercer Island, WA25,8204510.0%
      Source: The Mercer Island, WA 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.