San Anselmo Weather

May is San Anselmo's sweet spot, with highs around 74 degrees, a comfort score of 93, and nearly 13 hours of sunshine daily. April runs a close second with similar excellent conditions, while July and August bring warm, sunny weather in the low 80s. If you prefer to avoid crowds and still enjoy outstanding weather, March is underrated with highs in the mid-60s, 11 hours of sunshine, and minimal fog. The Ross Valley's inland position provides naturally pleasant temperatures year-round compared to coastal areas, making spring the ideal time for experiencing everything the town has to offer.

San Anselmo typically runs 5-15 degrees warmer than the immediate coast. While coastal areas might linger in the low 50s, San Anselmo sits in the low 70s during summer months. This warmth comes from its inland position in Ross Valley, sheltered from the persistent marine layer that affects the coast. Learn more about Bay Area microclimates that create these temperature variations within just a few miles. Winter temperatures are more similar to the coast, but San Anselmo still benefits from the valley's slightly milder conditions and lower wind exposure.

Absolutely, especially from April through October. Spring and early summer are ideal with temperatures in the low-to-mid 70s, abundant sunshine, and minimal fog. July and August are warmest at around 80 degrees but remain comfortable. Fall remains pleasant through September with highs around 70 degrees. Winter outdoor dining is trickier, with November and December averaging only 5-6 hours of daily sunshine and frequent rain. Save your outdoor dining experiences for late spring and early fall when conditions are most inviting and the temperature doesn't drop quickly after sunset.

San Anselmo averages less than 2 hours of morning fog daily over an 18-month period, which is quite low for the Bay Area. Summer months see almost no fog, ranging from 0.6 to 0.9 hours. June can see slightly more at 2.5 hours as the marine layer occasionally pushes inland. Late fall and early winter show the most fog, reaching 3-4 hours in October and November. This limited fog is one of San Anselmo's major advantages, especially compared to closer-to-coast neighborhoods that experience persistent morning cloud cover that can last well into the afternoon.

San Anselmo averages around 263 perfect weather days annually, which translates to roughly 9.6 hours of sunshine per day on average. Spring and early summer dominate with May and June regularly hitting 12-13 hours of direct sunlight. Even the darker months like November average nearly 6 hours of daily sun. This abundance of sunshine makes San Anselmo an excellent choice for anyone sensitive to gray skies or seeking to maximize outdoor time. The town's inland valley position shields it from the persistent fog that plagues areas just 5-10 miles west toward the coast.

November through January is San Anselmo's rainy season, with November bringing nearly 6.5 inches and January around 7 inches. The town experiences roughly 71 rainy days per year, concentrated in fall and winter months. October marks the transition with 3.8 inches, while February tapers to under 3 inches. Understanding atmospheric patterns explains why the Bay Area peaks in late fall rather than true winter. Spring and summer are remarkably dry, with May, June, July, and April seeing virtually no rainfall, making those months ideal for planning outdoor activities.

Spring and summer call for light layers: t-shirts, shorts, and a light jacket for early mornings when temps hover in the 50s. Sunglasses and sunscreen are essential given the 12-plus hours of daily sunshine. Fall is similar but add a sweater as mornings dip into the 40s. Winter requires a real rain jacket, umbrella, and warmer layers, as temps drop to the 40s-50s and rain is frequent. Year-round, layers are your best strategy for Bay Area weather, since morning fog and afternoon sun can create 10-15 degree swings within a single day.

San Anselmo summers are warm but rarely extreme. July and August typically peak around 80-82 degrees with comfort scores in the 88-92 range, making them very pleasant without feeling oppressive. September remains warm at around 70 degrees. The town rarely experiences the intense heat waves that inland valleys suffer through. Historical data shows highs consistently in the high 70s to low 80s rather than the 90s common in the Central Valley or southern Bay Area. This moderation comes from coastal air influences and the valley's geography, making San Anselmo genuinely comfortable for those sensitive to heat.

Ross and Fairfax experience nearly identical conditions, all benefiting from the same inland Ross Valley climate. Elevation differences are minimal, so temperature, sunshine, and fog patterns are essentially the same. Larkspur and Kentfield are equally comparable. The real differences emerge when comparing to San Rafael downtown, slightly more exposed to coastal influences, or destinations further inland toward the hills that experience more extreme temperature swings.

December is probably the worst month to visit for weather. It averages just 6 hours of daily sunshine, with 2.6 hours of morning fog and 3.7 inches of rain spread throughout the month. Comfort scores drop to 64 out of 100, the lowest of the year. If you must visit in winter, January and February offer the seasonal patterns typical of Bay Area winters, which is predictably gray and wet. March shows significant improvement with returning sunshine, warming temperatures, and lower rainfall, making it a much better choice for a late-winter visit.