Fairfax Weather

May is consistently Fairfax's standout month, with highs around 74 degrees, exceptional sunshine at 13.2 hours daily, and virtually no rain. April and July are close seconds, offering similar conditions with average comfort scores in the low 90s. If you're planning a spring or early summer trip, these months deliver the most reliable weather for outdoor activities. The town's 263 perfect-weather days annually cluster heavily in these warmer months, though even winter days often feel pleasant thanks to the 148-foot elevation that keeps things slightly milder than you'd expect in the North Bay.

Outdoor dining works well from April through October, when highs range from 73 to 84 degrees. June, July, and August are your most comfortable months for al fresco eating, though morning fog can linger until late morning during summer. From November through March, temperatures drop into the upper 50s, making outdoor dining chilly but doable if you dress warmly. The real limitation is rain rather than cold: October through January sees significant rainfall, up to 7 inches in some months, so a covered patio helps. Late spring and early fall give the best balance of warmth and dry conditions for outdoor dining.

Fairfax averages 1.8 hours of morning fog daily across the year, but it varies dramatically by season. November sees the most fog at 4.3 hours per day, while April barely experiences any at just 0.4 hours. Summer months typically have light fog lingering until mid-morning, clearing to brilliant sunshine by noon. This modest fog pattern makes Fairfax notably sunnier than the coast yet still benefits from the cooling marine influence. If you're sensitive to fog, visit in April or May when mornings are clearest, and avoid November when the fog really sets in. The morning fog in the Bay Area follows predictable patterns tied to the season and marine layer.

Winter is wet in Fairfax, with November and January being the soggiest months, bringing 6 to 7 inches of rain. The rainy season runs roughly October through March, but the intensity varies. October can surprise you with 5 inches, while February and December are more moderate at 3 inches or less. Spring dries out quickly: April sees just 0.08 inches of rain. The town averages 71 rainy days annually, so you'll encounter wet weather, but Fairfax typically stays drier than lower-elevation Bay Area locations. If you're planning outdoor activities like hiking or cycling, the rainiest month in the Bay Area pattern applies here too, so plan accordingly.

Fairfax sits at a comfortable elevation sweet spot. It's warmer than Mt. Tamalpais East Peak, which gets colder and cloudier due to altitude, but cooler than lower-elevation areas like downtown San Rafael. The elevation difference of just 148 feet keeps it pleasantly temperate year-round without the extreme conditions of higher peaks. Fairfax also benefits from slightly different microclimatic influences than nearby towns: the geography around San Anselmo and Ross creates subtle variations in how quickly morning fog burns off. If you want to understand why Fairfax feels different from its neighbors, the Bay Area's many microclimates explains this beautifully.

Layer everything. Even in warm months, bring a light jacket for mornings when fog hasn't cleared or in the shade under Mt. Tam's canopy. Summer highs hover around 80 degrees, but mornings and evenings dip to the mid-50s, making a sweater essential. Winter requires genuine cold-weather gear: expect highs in the mid-50s and lows in the mid-40s, with frequent rain. Long pants, waterproof jackets, and good hiking boots work for any season. Since Fairfax draws cyclists and hikers, moisture-wicking layers beneath a windproof outer shell handle both temperature swings and light precipitation. The Bay Area demands layering strategy more than almost anywhere else, and Fairfax exemplifies why.

Yes, elevation and tree cover create palpable variations. Lower, more open areas near town center reach higher temperatures and clear of fog faster, while shaded spots near forests or trails stay cooler and foggier longer. The Marin County terrain, with its dense redwoods and proximity to Mt. Tam, channels wind and moisture in ways that make one neighborhood feel noticeably different from another just a few blocks away. This is part of why the Bay Area is famous for extreme microclimates. If you're choosing where to stay or which trail to hike, understand that a sunny afternoon in one location might mean lingering clouds just upslope. These subtle variations reward local knowledge.

Late spring through early fall is ideal, particularly May, June, July, and August, when you get 10-13 hours of daily sunshine, comfortable temperatures in the 75-84 degree range, and minimal rain. Trails are drier and visibility is excellent. Fall can work too, though October brings more rain and afternoon clouds increase. Avoid November through February when trails become muddy, afternoon visibility drops, and temperatures dip uncomfortably. Even in summer, expect cool mornings around 55 degrees and bring layers for shade or higher elevations. The best months for Bay Area hiking data confirms that Fairfax's May-August window aligns with the Bay Area's peak hiking season, though local microclimates mean conditions can shift quickly.

Fairfax averages 9.6 hours of sunshine daily across the year, which is genuinely sunny for the North Bay. Late spring and summer are spectacular: May, June, and July deliver 12-13 hours of daily sunshine, making for long, bright days perfect for outdoor activities. Even autumn holds strong at 8.5-9.5 hours through September. Winter is the trade-off: November and January drop to around 6 hours, and December to 6.1 hours, contributing to the season's gloomier feel. The high sunshine hours during spring and summer explain why April, May, and July consistently top the comfort score charts at 92-93. If you're chasing light, visit between April and September.

Wind is generally not a dominant factor in Fairfax compared to exposed coastal or ridge-top locations. The town's 148-foot elevation and surrounding terrain provide shelter from the worst of the Bay Area's notoriously strong winds. You might notice afternoon wind picking up during summer, especially in May and June, but it's typically gentle compared to higher elevations or the open coast. Calmer conditions occur in late summer and fall, particularly August through October. If wind sensitivity matters for your plans, aim for late August or September when conditions are usually gentler. Understanding the Bay Area's wind patterns helps you appreciate why Fairfax actually feels relatively sheltered.