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United States › California › San Francisco County › Climate Station SAN FRANCISCO DWTN, CA US Distance 33.2 mi Normals 1991–2020

30-year climate normals

San Francisco County Climate and Weather Averages

Hottest month — September

70.2°

average daily high. The coldest month is January, averaging a low of 46.6°F.

San Francisco County gets 22.89" of precipitation a year, and 59% of it falls in Dec, Jan, Feb.

Temperature through the year

Each bar spans the average daily low to the average daily high for that month.

60° JanFebMarAprMayJunJulAugSepOctNovDec
MonthAvg highAvg low Precip
January 57.8° 46.6° 4.40"
February 60.4° 47.9° 4.37"
March 62.1° 48.9° 3.15"
April 63.0° 49.7° 1.60"
May 64.1° 51.4° 0.70"
June 66.5° 53.0° 0.20"
July 66.3° 54.4° 0.01"
August 67.9° 55.5° 0.06"
September 70.2° 55.6° 0.10"
October 69.8° 54.4° 0.94"
November 63.7° 50.7° 2.60"
December 57.9° 47.0° 4.76"

Rainfall by month

San Francisco County has a distinct wet season. 59% of the year's precipitation arrives in Dec, Jan, Feb.

January 4.40"
February 4.37"
March 3.15"
April 1.60"
May 0.70"
June 0.20"
July 0.01"
August 0.06"
September 0.10"
October 0.94"
November 2.60"
December 4.76"
Annual total 22.89"

What this climate costs you

Degree days measure how hard a building has to work to stay comfortable. They are the reason two identical houses have very different power bills, and they are the link between the weather here and what you pay every month.

Cooling degree days How much air conditioning the climate demands 121
Heating degree days How much heating the climate demands 2,781
Approximate annual cooling cost At 33.25¢/kWh, California average $40
Approximate annual electric heating cost Lower where heating is gas rather than electric $324

These are rough planning figures from degree days and the state electricity price, not a bill estimate. House size, insulation and fuel type move them a lot. See the full cost of owning a home in San Francisco County, where electricity is one line of eight.

Common questions

What is the weather like in San Francisco County?

San Francisco County averages a high of 70.2°F in September and a low of 46.6°F in January. Annual precipitation is 22.89 inches, with essentially no snow.

When is the rainy season in San Francisco County?

The wettest stretch is Dec, Jan, Feb, which accounts for 59% of the year's precipitation. That is a pronounced wet season rather than rain spread evenly through the year.

How hot does it get in San Francisco County?

The average daily high in September, the hottest month, is 70.2°F. That drives 121 cooling degree days a year, which is what your air conditioning has to work against.

Does it snow in San Francisco County?

Effectively no. Measurable snowfall is rare in San Francisco County.

Sources

  • Temperature, precipitation and snowfall normals — NOAA National Centers for Environmental Information, 1991–2020 Monthly Climate Normals, station SAN FRANCISCO DWTN, CA US (USW00023272), 33.2 miles from the county centroid.
  • Heating and cooling degree days — NOAA, same station and period.
  • Electricity price — US Energy Information Administration, Electric Power Monthly Table 5.6.A, California residential average.
  • Wet-season share is the wettest three consecutive months as a percentage of annual precipitation, calculated from the monthly normals.