Windsor Weather

Windsor sits at just 98 feet in northern Sonoma County, and its weather reflects a classic inland valley pattern: warm, dry summers and mild, wet winters. The annual average high is 73°F and the average low is 49°F, which puts Windsor solidly in the comfortable range for most of the year. The town earns 9.4 sun hours per day on average, and the historical data backs that up with 283 perfect days per year. Fog is a factor, with about 73 foggy days annually, but the fog here tends to burn off earlier than it does along the coast or in Santa Rosa to the south. Summers are genuinely warm, with June highs averaging 91.5°F and July averaging 88.2°F. Winters are cool and wet but rarely cold, with December and January highs hovering around 59 to 60°F. The overall comfort score of 84 out of 100 makes Windsor one of the more reliably pleasant towns in the North Bay. If you want the full seasonal picture for the region, the Bay Area four seasons guide is a good starting point.

Windsor gets less summer fog than the coast or the Bay itself, but it is not fog-free. The town averages 73 foggy days per year, and in summer that fog usually arrives overnight or in the early morning, then clears by mid-morning as the inland heat builds. By noon on most July and August days, Windsor is sunny and warm. That said, on days when the marine layer is particularly strong, the fog can linger into the afternoon in pockets of the valley. The key is the timing. Fog in Windsor is a morning condition in summer, not an all-day event. Compare that to the coast or the western Sonoma hills around Forestville, where the marine layer can sit through most of the day. Windsor's 1.6 average fog hours per day confirms this pattern: the fog is real but brief. The Bay Area microclimates article explains why the combination of coastal gaps, valley orientation, and inland heating creates such different fog experiences within a short drive.

April, May, and June are the best months to visit Windsor for weather, and the numbers strongly support this. April has an average high of 78.2°F and a comfort score of 93, the highest of the year. May follows closely at 80.6°F and a comfort score of 91. June pushes into the warmer end at 91.5°F but still earns a comfort score of 84, making it excellent for outdoor time if you like genuine summer heat. Spring in Windsor is particularly appealing because the hills are green, wildflowers are out, rainfall has tapered off, and temperatures are warm without the scorching heat that July can bring. The shoulder months of March (67.5°F, comfort 88) and September (82.6°F, comfort 86) are also strong options. September is worth highlighting because it is one of the warmest and most reliably sunny months, and the tourist crowds thin out noticeably after Labor Day. The worst weather months are December, November, and January, when rain is most likely and comfort scores drop to the 70s. Windsor still gets 74 rainy days per year, concentrated in the winter months.

Windsor gets genuinely hot in summer, especially compared to Bay Area coastal spots. June averages 91.5°F for the high, which is the peak of the year. July averages 88.2°F and August 85.6°F. These are real heat numbers, not just warm afternoons. Occasional heat waves push Windsor above 100°F, particularly in June and September when offshore flow patterns stall over the North Bay valleys. September is an interesting case because it often rivals or exceeds summer temperatures while feeling less humid. The September hotter than July article explains the meteorology behind this pattern, which Windsor experiences clearly. The practical implication is that summer visits to Windsor should account for afternoon heat. Mornings and evenings are comfortable, but between about 1pm and 6pm in June and July, plan for temperatures in the high 80s to mid-90s. A hat and sunscreen are not optional. Nearby Healdsburg has a very similar summer heat profile, while the coast runs 15 to 25 degrees cooler.

Windsor winters are cool, grey, and wet by North Bay standards, but they are mild compared to most of the country. December and January average highs of 60.4°F and 59.6°F respectively, with average lows in the mid-to-upper 40s. Frost is possible on clear cold nights but not a regular feature. Snow in Windsor is extremely rare, essentially a novelty event that happens once every several years at most and melts by mid-morning. The real winter story is rain. Windsor gets 33.9 inches of precipitation per year, and the bulk of it falls between November and March. The rainiest months in the Bay Area guide covers the regional patterns, and Windsor fits the North Bay model well: December and January are the soggiest, with multi-day rain events common. Comfort scores still hold up reasonably well by the data, December scoring 85, which reflects that when it is not raining, winter days in Windsor are often clear and pleasant. But you should pack rain gear for any extended winter visit. The vineyards surrounding town look beautiful in the wet season if you can catch a break between storms.

Windsor is not particularly windy by Bay Area standards. Positioned in the Santa Rosa Plain north of the city, it is sheltered from the strong afternoon westerlies that funnel through the Petaluma Gap and hammer spots further south. Summer afternoons bring a reliable onshore breeze from the northwest that typically runs 10 to 15 mph, which is enough to make 90°F days feel comfortable rather than stifling. This afternoon wind is actually one of Windsor's better weather features. It arrives around 2 or 3pm on most summer days, takes the edge off the peak heat, and dies down by evening. Winter storms can bring gusty winds during frontal passages, occasionally reaching 30 to 40 mph, but sustained wind is not a signature Windsor weather trait. The town's comfort score of 84 reflects this: wind is not pulling scores down the way it does in exposed coastal or hilltop locations. If wind sensitivity is a concern, Windsor is a solid choice compared to hillier Sonoma County terrain.

What to wear in Windsor depends heavily on the season and, in summer, the time of day. For summer visits, the layering advice applies in reverse of the coast: you can arrive in the morning in a light jacket when it is 58°F, strip down to a t-shirt by late morning, and possibly need sun protection gear for the hot afternoon. Sunscreen and a hat are genuinely necessary in June through September. For spring and fall, layers are the answer. Mornings in April can be in the low 50s and afternoons can reach the upper 70s or low 80s, so a light fleece or jacket you can tie around your waist is the right call. The dressing in layers for Bay Area weather guide applies here, though Windsor's swings are more vertical (cold morning to hot afternoon) than the coast's fog-in-sun-out pattern. For winter, a waterproof layer is essential from November through March. Temperatures rarely demand a heavy winter coat, but a rain jacket and waterproof shoes will get a lot of use. Wool or fleece midlayers work well for the cool evenings year-round.

Windsor sits in a comfortable middle ground among its North Bay neighbors. Compared to Santa Rosa just six miles south, Windsor tends to be slightly warmer in summer and has a similar rainfall pattern. The cities are close enough that their weather is often indistinguishable on any given day. Healdsburg, about eight miles north, runs a bit warmer still in summer because it sits slightly more sheltered in the Russian River valley. Forestville to the west is meaningfully different: closer to the coast, it gets more fog, lower summer highs, and more marine influence. Windsor's combination of warmth, limited fog burn-off delay, and high comfort scores (84 overall, 93 in April) puts it among the more reliably pleasant residential towns in Sonoma County. It does not have the dramatic heat of interior valleys like Cloverdale, nor the persistent summer fog of the coast. The Bay Area microclimates explainer covers why towns this close can still have meaningfully different weather, primarily due to coastal gap alignment and valley topography.

Windsor gets 33.9 inches of rain per year, distributed across about 74 rainy days. That puts it in a moderately wet category for the Bay Area, wetter than most of the South Bay and inland valleys, but similar to other North Bay towns. The rainy season runs from roughly November through April, with December and January being the wettest months. During this period, multi-day atmospheric river events are responsible for the majority of annual rainfall. A single storm in January can drop 3 to 5 inches of rain over a few days, then give way to a week of blue skies. That boom-and-bust pattern is characteristic of California's Mediterranean climate. April marks the transition: it can still have wet spells early in the month, but by late April the likelihood of rain drops sharply and the spring dry season is effectively underway. May through October is reliably dry, with summer rainfall near zero. If you are planning a visit around outdoor wine country activities, May through October is essentially rain-safe. November through March requires a flexible itinerary and solid rain gear.