30-year climate normals

Marin County Climate and Weather Averages

Hottest month — August

81.3°

average daily high. The coldest month is December, averaging a low of 42.1°F.

Marin County gets 34.45" of precipitation a year, and 64% 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.

Month	Avg high	Avg low	Precip
January	56.9°	42.6°	7.13"
February	61.1°	44.0°	6.94"
March	64.8°	45.5°	4.42"
April	67.8°	47.5°	1.99"
May	72.0°	50.6°	0.94"
June	77.9°	53.5°	0.15"
July	80.9°	54.9°	0.00"
August	81.3°	55.5°	0.05"
September	80.7°	54.4°	0.07"
October	74.9°	51.4°	1.46"
November	64.6°	46.0°	3.49"
December	57.1°	42.1°	7.81"

Rainfall by month

Marin County has a distinct wet season. 64% of the year's precipitation arrives in Dec, Jan, Feb.

January 7.13"

February 6.94"

March 4.42"

April 1.99"

May 0.94"

June 0.15"

July 0.00"

August 0.05"

September 0.07"

October 1.46"

November 3.49"

December 7.81"

Annual total 34.45"

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 486

Heating degree days How much heating the climate demands 2,481

Approximate annual cooling cost At 33.25¢/kWh, California average $162

Approximate annual electric heating cost Lower where heating is gas rather than electric $289

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 Marin County, where electricity is one line of eight.

Common questions

What is the weather like in Marin County?

Marin County averages a high of 81.3°F in August and a low of 42.1°F in December. Annual precipitation is 34.45 inches, with essentially no snow.

When is the rainy season in Marin County?

The wettest stretch is Dec, Jan, Feb, which accounts for 64% 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 Marin County?

The average daily high in August, the hottest month, is 81.3°F. That drives 486 cooling degree days a year, which is what your air conditioning has to work against.

Does it snow in Marin County?

Effectively no. Measurable snowfall is rare in Marin County.

Sources

Temperature, precipitation and snowfall normals — NOAA National Centers for Environmental Information, 1991–2020 Monthly Climate Normals, station SAN RAFAEL CIVIC CTR, CA US (USC00047880), 12 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.