Cotati Weather

April is Cotati's standout month. With an average high of 72 degrees, almost zero morning fog (just 0.5 hours), and nearly 13 hours of sunshine daily, April hits that sweet spot between warmth and comfort. The 92 comfort score is the highest in the 18-month dataset. July follows closely at 79 degrees with a 91 comfort score and 11.6 hours of daily sunshine. May is equally impressive at 90 comfort with highs near 73 degrees. These three months consistently deliver the best outdoor weather: warm enough for t-shirt weather midday but cool enough in the mornings and evenings to avoid oppressive heat. The Cotati plaza, with its distinctive hexagonal design, comes alive during these months when the weather is genuinely cooperative.

Cotati and Petaluma sit close enough geographically that their overall weather patterns are similar, but subtle differences emerge. Cotati averages slightly more sunshine and a touch more warmth year-round due to its slightly higher elevation and inland position. Petaluma, closer to Petaluma Creek and the southern marshlands, sees a bit more marine layer influence in summer mornings. Both towns experience the same rainfall totals and seasonal rhythm, but Cotati's downtown plaza tends to feel warmer during spring and fall when you are comparing back-to-back visits. The difference is more noticeable to longtime residents than casual visitors, but it reflects how the Bay Area's microclimates vary significantly within just a few miles. For practical purposes, forecast accuracy is nearly identical between the two.

April through October, Cotati's weather consistently supports outdoor dining. April, May, and July average highs between 72 and 79 degrees, making afternoon and early evening outdoor seating genuinely pleasant. Summer months bring temperatures comfortable for t-shirts and light jackets at dusk. The real challenge is not temperature but timing: June sees 3.1 hours of morning fog on average, so breakfast might mean waiting for the sun to clear the marine layer, but lunch is solid. Winter months (November through January) see highs only in the upper 50s and early 60s, with November bringing 6.7 inches of rain. Outdoor dining becomes viable on crisp, clear afternoons but impractical during the frequent rainy stretches. September and October offer excellent shoulder-season dining with warmth still present but fewer of the summer tourists crowding the plaza.

Cotati averages about 2 hours of morning fog daily, which is moderate for the inland North Bay. The town's 115-foot elevation helps it stay above the marine layer more often than sea-level coastal towns. Summer months (June through August) see the most fog: June peaks at 3.1 hours, while July and August average around 1.8 hours. April through May and September onwards typically clear within 1 to 2 hours, leaving clear skies by mid-morning. This is considerably less than San Francisco or coastal areas like Point Reyes, which experience thicker, more persistent marine layers. If you are planning outdoor activities, morning fog rarely requires rescheduling. Understanding why morning fog forms in the Bay Area helps set realistic expectations: it is normal and typically brief in Cotati.

Layers are essential year-round. Even on warm April or July days reaching 70 to 80 degrees, bring a light windbreaker or fleece for mornings when fog lingers and temperatures sit in the 50s. The temperature swing from sunrise to midday can exceed 15 degrees, and the early morning chill surprises many visitors. Fall and winter require more substantial layering: bring a proper fleece or sweater since mornings and evenings drop to the 40s from October onward. A waterproof or water-resistant jacket is non-negotiable from October through February when rain averages 3 to 7 inches monthly. Comfortable walking shoes matter since Cotati's plaza invites casual strolls, and wet pavement is common during the rainy season. Sun protection is often overlooked: Cotati averages 9.2 hours of daily sunshine annually, and reflected light off plaza surfaces amplifies UV exposure. Sunscreen and sunglasses are worthwhile even on mild days.

November is the rainiest month with 6.7 inches, followed by December at 3.7 inches and January at 7.4 inches. October marks the transition into the wet season, bringing 3.7 inches after the dry summer. The Bay Area's rainiest months follow a predictable pattern, and Cotati fits this timeline precisely. February sees 4.4 inches, then March starts to taper off at 0.5 inches. The dry season is genuinely dry: June through September combined bring only 0.4 inches of rain. September is the last gasp of moisture with 1.8 inches, while spring (March through May) becomes increasingly dry and sunny. The roughly 69 rainy days per year concentrate in winter, meaning many days see drizzle rather than dramatic downpours. Spring sunshine and lack of rain (near zero precipitation in May) make it an excellent counterpoint to winter's gray damp.

Cotati and Santa Rosa sit just a few miles apart and share nearly identical climates. Both occupy similar elevations in the North Bay and experience the same seasonal weather patterns and rainfall totals. The primary difference is that Santa Rosa, sitting slightly further inland away from any coastal marine influence, can reach temperatures a degree or two warmer in summer and early fall. Cotati catches gentler bay breezes and retains slightly more marine layer influence in early summer mornings. Both see the same comfortable spring and fall temperatures (65 to 75 degrees), the same winter lows, and the same summer warmth in the high 70s. For practical purposes, if you are choosing between the two based on weather, consider what activities suit you rather than climate: both towns deliver essentially identical conditions. Forecasts from either location apply reasonably well to the other.

Cotati edges out Sebastopol in warmth and sunshine. Sebastopol, nestled among redwoods and slightly higher in elevation with more coastal influence, stays a couple degrees cooler year-round. Cotati's July highs reach 79 degrees while Sebastopol sits in the mid-70s. Both see similar fog patterns and rainfall, but Sebastopol's forested terrain creates shadier conditions and morning marine layer tends to linger longer. Cotati's open terrain allows faster fog burn-off and more direct sunshine hours daily. Sebastopol appeals to visitors seeking cooler, mistier mornings and forest atmosphere. Cotati suits those wanting reliable warmth and sunshine. The difference is subtle enough that regional weather patterns matter more than the microclimate distinction: if a warm, sunny day is forecast, both towns deliver it reasonably well.

November ranks lowest with a 67 comfort score, followed by December at 69 and January at 72. November brings 6.7 inches of rain, temperatures only in the high 50s (57 to 60 degree highs), and just 5.7 hours of daily sunshine. The month feels gray and drizzly rather than dramatically stormy. December compounds the misery with temperatures dropping further to 58 degrees and nearly 4 inches of rain. Days are short (6.1 hours of sunshine), and the combination of persistent cloud cover and frequent drizzle creates a relentless damp feeling. January follows with similar conditions: 7.4 inches of rain, temperatures around 59 degrees, and short days. Fortunately, this is still milder than inland areas and dramatically different from harsher climates. If you must visit Cotati in winter, embrace the quiet charm, coffee culture, and fewer tourists rather than expecting ideal weather.

Cotati averages 9.2 hours of sunshine daily, which is excellent for the Bay Area. Spring is the sunshine champion: April delivers 12.9 hours, May 12.8 hours, and June 11.6 hours of daily sunshine. July sustains 11.6 hours, and August stays strong at 9.7 hours. These months deliver long, genuinely bright days that make outdoor activities rewarding. Fall is solid but declining: September sees 7.9 hours, October 6.8 hours. Winter drops dramatically: November reaches only 5.7 hours, December 6.1 hours. Spring (March through May) is when Cotati shines brightest with near-peak daylight hours and the highest comfort scores (82 to 92 range). If you prioritize sun, plan visits from April through September. The data shows roughly 261 perfect days annually, suggesting outdoor opportunity windows are genuinely plentiful and well-distributed across the year.

Cotati avoids weather extremes, which is one of its charms. July represents the warmest month with highs around 79 degrees and lows around 55 degrees. August is nearly identical. Even during peak summer, temperatures stay moderate compared to inland valleys that regularly hit 90 degrees or higher. The coolest months are December and January, with highs only in the upper 50s (58 to 59 degrees) and lows in the low 40s (39 to 42 degrees). Freezing temperatures are uncommon at Cotati's modest 115-foot elevation, and heat waves pushing into the 90s are equally rare. This narrow temperature band (39 to 79 degrees across the year) is actually Cotati's strength: you get reliable, comfortable weather without climatic extremes. Understanding the Bay Area's four seasons shows how Cotati's moderate profile exemplifies the region's temperate climate. Pack accordingly and you will stay comfortable year-round.