Weather in Marin

Weather

The weather in Marin County is truly fantastic. Marin County average rainfall is 45-50 inches; the summer doesn't get too hot and the winter doesn't get too cold. However, there are a few weather factors that you should know about when searching for a home in Marin County-- the main variable to consider is: 1) fog and 2) the cold wind that blows along the edge of the fog in the afternoons, through valleys and over ridges.

  • FOG:
    • Why does the fog develop? it all boils down to something called the Coriolis Effect (http://en.wikipedia.org/wiki/Coriolis_effect) which causes the Ocean currents to flow from North to South on the West Coast causing the water and the air directly above it to stay cool and moist (50-55 degrees ) meanwhile the air over the land gets quite warm and dry especially during the summer. The differential of these two air masses creates fog, aka "The Marine Layer".
  • WIND: Three related phenomena to the fog are:
    1. The Bay Area thermal effect-which is when the hot air over Oakland and the East Bay rises, and the cold air from the coast rushes in underneath
    2. The Venturi Effect which increases the velocity of wind when the space through which it is blowing is reduced- think Golden Gate
    3. Bernoulli's Principle wind blows harder when it is forced over hills.
  • These are the reasons why:
    1. The sailing, windsurfing, kitesurfing, and glider flying in the entire bay area is world-class
    2. why people move from San Francisco to Marin County (quote "the Coldest winter of my life was a Summer in San Francisco" Mark Twain)
    3. Why it is important to work with a local realtor who knows the weather patterns in the different neighborhoods- 100 yards in either direction can mean a differential of 15 degrees or more during a normal summertime afternoon.
  • The Four Areas of Marin County-- South, Central, North and West Marin
  • As you drive over the Golden Gate Bridge the first 4 towns you reach are Sausalito, Mill Valley, Tiburon and Belvedere- aka "Southern Marin".
    • The Southern Marin weather is a huge improvement over San Francisco weather. Marin can have beautiful long warm summer days when at the same time across the bridge in San Francisco the weather is grey, cold and disheartening. This pattern can continue for weeks on end in the summer.
    • As you drive north past Mill Valley on 101, you'll drive over a ridge that separates "Southern Marin" from "Central Marin"
  • "Central Marin" includes Corte Madera, Larkspur, Greenbrae, Kentfield, Ross, San Anselmo, Fairfax and parts of southern San Rafael
    • "Central Marin" is slightly more removed from the maritime air and thus is a bit warmer in the summer than Southern Marin and slightly cooler in the winter-as you move north and west through these towns this effect increases.
  • "Northern Marin", the area includes northern parts of San Rafael and areas north, exemplified by the town of Novato.
    • "Northern Marin is much more removed from the maritime influence and is much warmer in the Summer (gets quite hot) and colder in the winter.
  • "West Marin"
    • Coastal Towns of Marin, north of Point Reyes which have very similar weather to San Francisco proper, with the exception Stinson Beach which is south of Point Reyes and is sheltered by several points (the largest of which is Point Reyes). Summertime in West Marin is dominated by the Marin Layer and when it isn't foggy, it can be breezy to downright windy in the Spring and Summer. All year around there are absolutely delightful beach days mixed in!!!

Seasons

The greatest myth about Central California, the San Francisco Bay Area and Marin County in particular is that we don't have seasons. The more involved one is with outdoor and Bay activities, you more conscious you will become of the distinct seasons and related weather patterns. Winter is cold with little fog, little wind, and great skiing in Sierras. Spring is warmer with beautiful long days, less fog than summer and very windy along the coast; summer is foggy along the coast with great sailing in the Bay and warmer inland (i.e. Napa, Sonoma, Medocino, Santa Cruz and Tahoe); and fall is the warmest of all with our Indian Summer lasting for part of September all of October, and parts of November and December.

Gardening:

These three areas (Southern Marin, Central Marin and Northern Marin) are all hospitable to similar plants, however in each region some will thrive more than others. Each winter there is always a period of 10 days to 2 weeks when a cold high pressure dominates the west coast shifting the jet stream south and cooling the nights into the mid to high 20's. If gardening specific plants is important to you, please pick up a copy of the "Western Garden Book" read the first 20 pages and then ask us how it applies to the weather subtleties in different neighborhoods.



Built by WebSight Design