TODAY MAY14
TEMPERATURE53
HUMIDITY89
PRESSURE
WIND COND.34 1.6
  • 6747
  • 6649Sat
  • 7048Sun
  • 6847Mon
  • 6948Tue
daynightWeather update from LOS ALTOS at

Key findings

  • The highest monthly average temperature in Portola Valley for July is 66.7 degrees
  • The lowest monthly average temperature in Portola Valley for January is 50.4 degrees
  • The most monthly precipitation in Portola Valley occurs in December with 2.6 inches
  • The air quality index in Portola Valley is 14% better than the national average
  • The pollution index in Portola Valley is 127% worse than the national average

Compare Portola Valley, CA Weather

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      Portola Valley 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°F61°F50°F2.4"
      February45°F63°F53°F2.4"
      March47°F67°F56°F2.0"
      April49°F70°F58°F1.3"
      May53°F73°F61°F0.3"
      June56°F77°F65°F0.2"
      July59°F78°F67°F0.0"
      August59°F78°F66°F0.0"
      September57°F80°F67°F0.1"
      October53°F75°F63°F0.7"
      November47°F67°F56°F1.3"
      December42°F60°F51°F2.6"

      Portola Valley 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.
      IndexPortola ValleyCaliforniaNational
      Air quality index435550
      Pollution index11,477,20018,106,7265,066,862

      Portola Valley 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

      Portola Valley air quality information

      PollutantTotal
      Arsenic0.070%
      Benzene0.110%
      Carbon Tetrachloride0.000%
      Lead0.160%
      Mercury0.090%

      Average monthly Portola Valley temperature with heat index

      Portola Valley monthly precipitation with daily maximum

      Portola Valley monthly snow depth with daily maximum

      Portola Valley monthly wind speed information

      Nearby cities with good air quality

      City, StatePopulationAir Quality IndexNational Avg.
      Pescadero, CA1,0403530%
      Lexington Hills, CA2,6173530%
      Loma Mar, CA1503530%
      Saratoga, CA30,8304314%
      El Granada, CA6,1324314%
      Portola Valley, CA4,5504314%

      Cities with similar population

      City, StatePopulationAir Quality IndexNational Avg.
      Niskayuna, NY4,5483726%
      Mullins, SC4,5534020%
      Gibraltar, MI4,547198%
      Madisonville, TX4,5464118%
      Cobleskill, NY4,5543726%
      Portola Valley, CA4,5504314%
      Source: The Portola Valley, 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.