Marin County Weather

Marin Weather Explained:

Marin County has great weather. It's one of the natural attributes that help make it one of the best places to live in the world.  It is said that is as close to perfect as you can get and still enjoy all four seasons.  One thing must be said about Marin and San Francisco weather, it is never idle talk.   When you visit the Bay Area, weather is a real subject.  Cross over the Golden Gate Bridge to Marin, and you will see a very different weather pattern on most days.  Usually, in the summer, most of San Franisco sits in fog, while you sit bayside in Marin.

It is important to understand that Marin is a county of extreme “microclimates”.  This is partially due to a Mountain range seperating the town (usually Mt. Tam) and coastal influence from the Bay or Pacific Ocean.  This is very important to keep in mind when vacationing in the San Francisco Bay Area.   Weather can vary in temperature, possibly jumping 15º between town to town only a few miles apart.   Summer fog can peel in from the ocean keeping things cool in southern Marin, but keeping things hotter in the central and northern parts of the county like San Rafael out to Novato.  Some parts of Marin suffer from prevailing winds, such as along the West Marin's coastline, or San Rafaels "Peacock Gap", while other towns nearby do not.  San Rafael, where the Marin Vista House is located, is a "hot spot" of Marin.  When the rest of the county is in fog or haze, the Marin Vista House usually is enjoying the sun.  :)


Like many people, out of towners assume the weather is the same throughout Marin County, varying only with the time of year.  Nothing is farther from the truth! Can you say microclimates??

     To start, there are days when it’s just plain hot or just plain cold throughout the Marin County.   However, there is a lot of variation through most of the year from town to town, in Marin.   Locals know this.   Since I can't talk like a weatherman, but have been raised here, put simply, temperatures get warmer about 1º, per mile, as you head north on Hwy 101 from Sausalito (beginning of Marin) to Novato (end of Marin line).  If you head out to West Marin, it can differ completely in climate - sometimes sitting in the sun with the rest of Marin, or fogged-in the whole day.   So, on any given day, especially spring, summer or fall, drive the 10 miles from Sausalito to San Rafael and there will be a temperature difference of around 10º due to that your gradually heading farther away from the San Francisco Bay and the Pacific coast as you head north.   When you head away from the coast and it's “marine layer”, the weather gets warmer.   Vice versa, the closer you get to the San Francisco Bay, Pacific Ocean, the cooler it becomes.   Please note, there are plenty of variations to this general rule, this is just the local "rule of thumb" on weather in Marin.


Amazingly, the difference between the shade, and standing in the sun, can be 10 degrees difference, “Marinites” term this “Nanoclimates”.

Spring, Summer and Fall:

     Marin is a county of four mild, distinct seasons, but is mainly dominated by seven warm weather months of May thru November, not a cold long winter. Marin features a long summer with a short spring and fall acting as transitions around our mild, short winters. Spring time starts in early May with average daytime temperatures in the 70’s, increasing to the mid or high 80’s by summer. Our warmest months are generally June thru October where it’s not uncommon to have warm spells for weeks at a time, right up until early November. Truly, we have a great, consistent Indian Summer. There is no smog and air conditioning in homes is rare, though not unheard of, especially in the more expensive homes.

     Marin county is known for its year round outdoor activities. These include, hiking, biking, skating, sailing on the bay, surfing, kayaking, fishing, camping, sightseeing or even bird watching. For things to do while it’s warm, visit the marin vacation website ( for great outdoor activities like Hiking and Biking, boating, or visiting one of our numerous Parks.


     Winter is a short season, beginning sometime after January 1st and ending sometime around the end of March. Winter officially starts whenever the rain decides to fall over Marin and snow blankets the Sierra Mountains, though this can be hit or miss. An “early” winter can mean rain in late November with some ski resorts open for Thanksgiving, yet it’s also not uncommon to play touch football on a warm Christmas day. The rainiest months though are easily January thru March where we get an average of 40 inches of rain.  Temperatures rarely get below 50º.