Things to Do in San Jose in September
September weather, activities, events & insider tips
September Weather in San Jose
Is September Right for You?
Advantages
- Post-summer shoulder season means 20-30% lower hotel rates compared to peak winter months, with excellent availability at downtown properties near San Pedro Square and Santana Row without advance booking requirements
- Perfect weather for outdoor activities with daytime temperatures averaging 24°C (75°F) and virtually zero rainfall - ideal for hiking the 1,100+ trails in nearby Santa Cruz Mountains and exploring Alum Rock Park's 13 miles (21 km) of trails without the oppressive July-August heat
- September harvest season brings exceptional farm-to-table dining experiences, with local farmers markets at peak abundance featuring heirloom tomatoes, stone fruits, and artichokes from nearby Gilroy and Watsonville farms - plus wine country day trips to Livermore Valley showcase crush season activities
- Major tech conferences and events create vibrant city energy, including San Jose Jazz Festival summer series wrap-up events, while avoiding the massive crowds and hotel price spikes of major convention months like February-March
Considerations
- Air quality can deteriorate during September wildfire season in California, with AQI occasionally reaching 100-150 on smoky days, requiring indoor activity backup plans and potentially limiting mountain visibility for photography
- Some family-oriented attractions get noticeably quieter as schools resume after Labor Day weekend, which means reduced operating hours at places like Happy Hollow Park and Zoo (closing at 4pm instead of 6pm) and fewer weekend event offerings
- Coastal fog patterns mean morning trips to nearby Santa Cruz or Half Moon Bay beaches often require waiting until 11am-noon for fog burn-off, reducing usable beach time compared to inland activities
Best Activities in September
Santa Cruz Mountains Hiking and Redwood Forest Exploration
September offers the absolute best conditions for exploring the ancient redwood groves just 30-45 minutes from downtown San Jose. With summer heat gone but winter rains not yet arrived, trails at Castle Rock State Park, Big Basin (check current wildfire recovery status), and Sanborn County Park are dry, well-maintained, and nearly empty on weekdays. Temperatures in the forest stay around 18-21°C (64-70°F) even when the valley reaches 27°C (80°F). The low humidity at 70% means comfortable hiking without the oppressive moisture of other seasons. Morning starts at 7-8am give you trails almost entirely to yourself.
Silicon Valley Tech Campus Tours and Museum Exploration
September weather with 70% humidity and mild 24°C (75°F) temperatures makes walking between outdoor tech campus landmarks comfortable. The Tech Interactive museum downtown is perfect for the 10 rainy days when you need indoor plans, but most September days allow for self-guided walks or bike rides past Apple Park's visitor center, Googleplex Android statue garden, and Facebook's campus murals. Early September still has summer intern energy before they depart mid-month. The Computer History Museum in Mountain View (15 miles/24 km north) offers 3-4 hours of air-conditioned exploration ideal for midday heat.
Livermore Valley Wine Country Day Trips During Crush Season
September is crush season in Livermore Valley wine country, just 45 miles (72 km) east of San Jose, when wineries harvest grapes and the energy is palpable. Unlike Napa's crowds and high prices, Livermore offers intimate tasting experiences at 50+ wineries with tasting fees typically 15-25 USD. The weather is ideal - warm 26-29°C (79-84°F) days perfect for outdoor patio tastings, low humidity at 70%, and virtually no rain to disrupt plans. Weekday visits in September mean you often have tasting rooms nearly to yourself. Watch crush activities, meet winemakers, and enjoy harvest-season food pairings.
San Pedro Square Market and Downtown Food Walking Routes
September evenings in downtown San Jose are perfect for food exploration, with comfortable 18-21°C (64-70°F) temperatures after 6pm and the 70% humidity dropping as sun sets. San Pedro Square Market's outdoor seating becomes prime real estate without summer's heat or winter's chill. The surrounding SoFA District, Japantown, and Little Portugal neighborhoods are walkable in 2-3 hours, covering approximately 3 miles (4.8 km) of diverse cuisines. September brings harvest-season menus featuring local produce. The lack of major conventions means restaurants have better availability than peak months.
Bay Area Stadium and Sports Venue Experiences
September means NFL season kicks off with San Francisco 49ers games at Levi's Stadium in Santa Clara (5 miles/8 km from downtown San Jose), plus Oakland Athletics baseball final season games, and San Jose Earthquakes soccer matches. September weather is ideal for outdoor stadium experiences - warm enough at 24°C (75°F) for comfortable seating but not the scorching heat of July-August. The UV index of 8 requires sun protection but evening games after 5pm offer perfect conditions. Pre-game tailgating culture and post-game celebrations in nearby bars give authentic local sports experiences.
Alum Rock Park Urban Wilderness and Mineral Springs Exploration
Just 15 minutes (8 miles/13 km) from downtown, Alum Rock Park offers 13 miles (21 km) of hiking trails through California's first municipal wilderness park, and September is the secret perfect month. Summer heat has broken but trails remain completely dry and safe - the 10 rainy days in September typically bring brief afternoon showers that cool things down rather than muddy trails. The historic mineral springs area provides shaded exploration when midday temperatures reach 27°C (80°F). Weekday mornings see mostly local regulars and serious hikers. The 70% humidity is manageable in the canyon's shade, and the UV index of 8 is blocked by oak canopy on forested trails.
September Events & Festivals
San Jose Jazz Festival Summer Series Finale
The summer jazz series typically concludes with final outdoor performances in early September at Plaza de Cesar Chavez and San Pedro Square. Free evening concerts showcase local and regional jazz artists, with the comfortable September evening temperatures around 18-21°C (64-70°F) making outdoor listening ideal. Bring blankets or low chairs, arrive 30-45 minutes early for good spots, and enjoy the downtown atmosphere with food vendors and local craft beer.
Harvest Festivals at Local Farms and Orchards
Multiple farms within 30-45 minutes of San Jose host September harvest celebrations, particularly in Gilroy (garlic country) and Morgan Hill areas. These working farm events feature u-pick opportunities for late-season fruits, farm-to-table dinners, and agricultural demonstrations. Not tourist-focused events but authentic local celebrations where you can buy directly from growers and experience California's agricultural heritage. Check individual farm websites as dates vary by harvest timing and weather.