Central Valley Wintertime Climate Averages

Annual and monthly averages for precipitation, dew point, dew point depression (DPD), sea level pressure (SLP), average temperature, max temperature (tmax), minimum temperature (tmin), visibility, wind speed, and NOx concentration. Data looks at fog season averages for variables, eg November-March. 'FogData' files includes number of fog days per year (days where visibility Daily averages were derived from hourly measurements. An daily measurements for all continuous variables were created by averaging measurements taken every 3 hours (0:00, 3:00, 6:00, 9:00, 12:00, 15:00, 18:00, 21:00). 7 of 8 hourly observations were required to calculate daily average. Each variable also includes a percent of measurements available for the month and year in a separate file. 65% of daily averages needed to be available in a month to determine a monthly average. All 5 months reported a monthly average in order to create a yearly average. Fog days and fog hours are episodic, thus 90% of hourly observations needed to be available to create an average. Sources:https://www7.ncdc.noaa.gov/CDO/cdoselect.cmdhttps://www.ncdc.noaa.gov/cdo-web/datatools/lcd.https://www.epa.gov/air-emissions-inventories/air-pollutant-emissions-trends-data https://www.arb.ca.gov/adam/