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Key findings

  • The highest monthly average temperature in Union City for August is 64.4 degrees
  • The lowest monthly average temperature in Union City for December is 49.2 degrees
  • The most monthly precipitation in Union City occurs in January with 3.5 inches
  • The air quality index in Union City is 14% better than the national average
  • The pollution index in Union City is 136% worse than the national average

Compare Union City, CA Weather

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      Union City 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
      January42°F58°F50°F3.5"
      February46°F61°F53°F3.3"
      March46°F64°F54°F2.6"
      April48°F66°F56°F1.8"
      May52°F69°F59°F0.6"
      June56°F73°F62°F0.1"
      July57°F75°F64°F0.0"
      August58°F76°F64°F0.0"
      September57°F76°F64°F0.2"
      October53°F72°F61°F1.4"
      November48°F66°F56°F1.3"
      December42°F58°F49°F3.2"

      Union City 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.
      IndexUnion CityCaliforniaNational
      Air quality index435550
      Pollution index6,427,29010,473,1902,726,193

      Union City air quality information

      MeasurementTotal
      Days measured365
      Days with good air quality263
      Days with moderate air quality98
      Days w/ poor A.Q. for sensitive groups4
      Days with unhealthy air quality0

      Union City air quality information

      PollutantTotal
      Arsenic0.010%
      Benzene0.110%
      Carbon Tetrachloride0.010%
      Lead0.010%
      Mercury0.003%

      Average monthly Union City temperature with heat index

      Union City monthly precipitation with daily maximum

      Union City monthly snow depth with daily maximum

      Union City monthly wind speed information

      Nearby cities with good air quality

      CityPopulationAir Quality IndexNational Avg.
      Danville, CA43,7584020.0%
      Blackhawk, CA9,4684020.0%
      Camino Tassajara, CA3,4564020.0%
      San Leandro, CA89,0394020.0%
      Castro Valley, CA62,8254020.0%
      Union City, CA73,5004314.0%

      Cities with similar population

      CityPopulationAir Quality IndexNational Avg.
      Milpitas, CA73,4474314.0%
      Appleton, WI73,4463726.0%
      Manteca, CA73,5704510.0%
      Dale City, VA73,384476.0%
      Loveland, CO73,360484.0%
      Union City, CA73,5004314.0%
      Source: The Union City, CA 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.