Plan your perfect Sonoma wine country celebration with 30 years of historical weather data. Sonoma's Mediterranean climate delivers a long dry season ideal for vineyard weddings, estate receptions, and outdoor gatherings from late spring through fall.
Based on 30 years of weather data, May through October offers ideal conditions for outdoor events in Sonoma. September and October stand out as the peak months — harvest season brings warm days, cool evenings, and virtually zero rain:
Historical averages based on 30 years of climate data (1995–2024) from the Sonoma weather station
| Month | Avg High | Avg Low | Rain Chance | Comfort Score | Event Rating |
|---|---|---|---|---|---|
| January | 58°F | 39°F | 39% | 0/100 | |
| February | 63°F | 40°F | 38% | 29/100 | |
| March | 66°F | 42°F | 34% | 60/100 | |
| April | 70°F | 44°F | 21% | 68/100 | |
| May | 76°F | 48°F | 13% | 95/100 | |
| June | 84°F | 52°F | 4% | 96/100 | |
| July | 87°F | 54°F | 0% | 70/100 | |
| August | 87°F | 54°F | 1% | 71/100 | |
| September | 85°F | 51°F | 3% | 97/100 | |
| October | 78°F | 48°F | 12% | 98/100 | |
| November | 66°F | 42°F | 27% | 54/100 | |
| December | 58°F | 39°F | 40% | 0/100 |
These statistics represent 30-year averages (1995–2024) from the Sonoma station. The Comfort Score (0–100) combines temperature and humidity during afternoon/evening hours. Sonoma runs warmer and drier than coastal Santa Barbara or San Diego — July and August are essentially rain-free but afternoon heat (87°F) pushes comfort scores into the Good rather than Excellent range. The sweet spots are May, June, September, and October, where warm days meet cooler evenings and negligible rain.
September and October are Sonoma's finest months for events — comfort peaks at 97–98/100, rain is virtually absent, and the vineyards turn gold and crimson. It's also harvest time, meaning the valley is at its most photogenic. Book 18+ months ahead for popular estate venues during these months.
The driest months of the year (0–1% rain), but midday heat reaches 87°F. Comfort scores of 70–71/100 reflect afternoon warmth. Plan ceremonies for late afternoon (5–6 PM) when temperatures drop to the mid-60s°F — evening events are very pleasant and reliably rain-free.
December through March brings Sonoma's rainy season (27–40% monthly rain chance) and cold nights. January and December comfort scores drop to 0/100 — outdoor events in these months require substantial covered infrastructure. If you must book a winter date, late March is the best bet as rain begins to taper.
Sonoma Valley runs slightly cooler and more coastal-influenced than Napa Valley, with more fog in morning hours. Both share essentially the same rain-free summer window. Sonoma tends to offer more intimate, family-owned estate venues compared to Napa's larger resort properties — ideal for events under 150 guests.
Explore hour-by-hour weather patterns, sunrise/sunset times, and comfort ratings for your specific event date in Sonoma.
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