Yountville Weather

April and May are your ideal windows. April brings warm but not oppressive temperatures, averaging 78-79°F with clear skies and 12.7 hours of daily sunshine. May follows close behind with highs around 82°F and even better sun at 12.9 hours daily. Both months deliver 91-92 comfort scores and virtually no rain. If you want to experience Yountville's outdoor dining scene at its peak, these spring months let you enjoy meals on patios without the summer haze or winter chill. June also works beautifully at 82°F with 12.3 hours of sun, though fog creeps in slightly earlier (1.7 hours) compared to earlier in spring.

Yountville runs significantly warmer than coastal Bay Area towns due to its protected location inland in Napa Valley. While coastal spots like Half Moon Bay or Pacifica rarely exceed 65°F in summer, Yountville regularly hits 85-90°F from June through September. The difference is most dramatic during heat events, when Yountville can feel 20-30°F hotter than the beach. This microclimate advantage comes from being sheltered from the cool Pacific currents and marine layer that dominate the coast. The valley's geography traps warm air, making it ideal for wine growing but challenging if you prefer cooler conditions. Learn more about why the Bay Area has such distinct microclimates.

Yountville gets far less fog than most Bay Area locations, thanks to its inland valley position. Historical data shows only 1.7 hours of morning fog on average, concentrated heavily in fall and winter. June through August are nearly fog-free at 0.6-1 hours, so morning walks on Main Street are crisp and clear. By contrast, coastal San Francisco neighborhoods can see 3-4 hours of fog during the same period. This less-foggy character is part of what makes Yountville pleasant for full-day outdoor activities. However, winter mornings (January-February) do bring more fog at 2+ hours, though it typically burns off by mid-morning. Understand how fog forms along California's coast.

June through September are your driest stretch, with measurable rain essentially nonexistent. July registers 0.02 inches, August 0.59 inches, and June just 0.03 inches. April and May are also excellent at 0.14 inches total. Fall and winter tell a different story: October through January brings 4.45 to 9.8 inches monthly, with January being particularly wet at 9.8 inches. If you're planning a wine country trip focused on outdoor activities, aim for May-September. December is a notable exception among wet months, with only 4.16 inches of rain but reduced sunshine at 5.8 hours daily. The dry season's reliable sunshine and minimal precipitation make it perfect for vineyard visits and patio dining.

Yountville reaches genuine summer heat from June through August, with highs averaging 84-89°F. July peaks at 89.5°F, making it warmer than San Francisco proper. However, comfort scores during these months remain excellent at 85-86 out of 100, thanks to low humidity and plentiful sunshine. The heat is dry and pleasant rather than sticky, which makes it feel less oppressive than similar temperatures in humid climates. September cools slightly to 73°F but maintains 85-comfort ratings. Compared to inland Central Valley towns that regularly hit 100°F+, Yountville stays manageable. If you prefer temperatures below 75°F, stick with April-May or September-October. For wine tasting and outdoor dining, summer heat pairs well with cold beverages and shaded patios.

Layer your clothing for Yountville, though the valley's consistent conditions make it easier than the coast. Spring and early fall (April, May, September, October) demand a light jacket or cardigan for morning and evening, when temperatures drop to the upper 40s-50s. Daytime sun is strong enough that you'll shed layers by afternoon. Summer (June-August) calls for lightweight clothing, sunscreen, and a sunhat for midday outdoors, but carry a sweater for air-conditioned restaurants or evening strolls. Winter is the only chilly season, averaging lows around 40-44°F with occasional frost, so bring actual coats and long sleeves. Comfortable walking shoes are essential year-round for exploring downtown and tasting rooms. Sunglasses are useful nearly every month, especially during high-sun periods (May-August with 12+ hours daily).

Yountville and Napa sit just 9 miles apart but experience slightly different climates due to subtle elevation and valley positioning differences. Yountville at 92 feet elevation is lower and more sheltered, while Napa sits slightly higher and more exposed to marine influences from the south. This makes Yountville marginally warmer and sunnier during peak season. Both towns share the core wine country weather pattern: hot, dry summers with minimal fog, cold wet winters, and glorious spring/fall shoulder seasons. However, Yountville's reputation as the more upscale culinary destination is partly weather-related: its position ensures more reliable outdoor dining weather and fewer rain interruptions during peak season. Explore how nearby areas differ.

November and December are your least comfortable months. November averages just 69-72 comfort scores with excessive rain (8.24 inches) and only 5.8 hours of daily sunshine. December dips to 66-84 comfort depending on rain, with similar rainfall and minimal sun. January is slightly less dismal at 73 comfort, though rainfall peaks at 9.8 inches and fog increases. These months transform Yountville from an outdoor-focused destination to an indoor wine-tasting one. Cold temperatures (highs around 59-60°F) and frequent rain eliminate comfortable patio dining and make walking between tasting rooms unpleasant. If you must visit winter, February is better than November at 77 comfort with decreasing rain. Conversely, avoid early October too, when rain spikes to 4.45 inches before the dry season fully establishes itself.

Late August through October encompasses grape harvest, and the weather is mixed. August through early September remain warm (73-84°F) with dry conditions perfect for field work, though comfort dips slightly as occasional afternoon clouds roll in. Mid-September marks the sweet spot: highs around 73°F with excellent comfort at 85 and minimal rain. Late September and October bring cooling temperatures (highs dropping from 73°F to 66°F) with increasing morning fog (up to 3.4 hours by late October). Rainfall becomes frequent, particularly from late September onward, peaking in October at 4.45 inches. The harvest actually benefits from slightly cooler conditions and morning fog, which slow ripening and concentrate grape sugars. Understand why September can be surprisingly warm.

Yountville in winter is not mild compared to California standards, though it's better than northern regions. January averages just 60°F highs and rainy conditions make outdoor exploration challenging. December and November are similar or colder. However, Yountville winters are far preferable to inland locations that dip below freezing or to foggy coastal areas. The key advantage is that winter days often include breaks of bright sunshine (5.8-7.8 hours daily), especially in late morning and afternoon. Indoor wine tasting, farm-to-table dining, and spa days are genuinely appealing in winter. Occasional warm days in the 65-70°F range appear randomly, perfect for quick outdoor walks. If you specifically want mild winter beach weather, seek the eastern Bay Area around Glen Ellen or further south. For wine country immersion with tolerable winter conditions, Yountville remains solid.