Monthly climate guide
San Jose weather in September
September in San Jose is typically hot, with average daytime highs around 30°C (85°F) and night-time lows near 13°C (55°F). The month usually brings about 3 mm of rain (very dry) and is mostly sunny. Daytime highs are about the same as August and 3°C warmer than October.
What stands out in September
- September brings early autumn to San Jose.
- September is San Jose's second warmest month.
- It's one of the drier months, with about 93% less rain than San Jose's average.
- Evenings cool off sharply: the daily range is around 17°C, so pack a layer.
Avg high
30°C
85°F
Avg low
13°C
55°F
Rainfall
3 mm
very dry
Humidity
61%
relative
Sky
16%
cloud · mostly sunny
San Jose weather by month
Show the monthly averages as a table
| Month | Avg high | Avg low | Rain | Humidity | Cloud cover |
|---|---|---|---|---|---|
| January | 15°C / 58°F | 5°C / 40°F | 92 mm | 83% | 54% |
| February | 16°C / 60°F | 5°C / 41°F | 86 mm | 81% | 44% |
| March | 17°C / 62°F | 6°C / 43°F | 97 mm | 82% | 51% |
| April | 19°C / 67°F | 7°C / 45°F | 38 mm | 78% | 39% |
| May | 22°C / 72°F | 9°C / 48°F | 14 mm | 73% | 31% |
| June | 27°C / 80°F | 11°C / 51°F | 6 mm | 65% | 16% |
| July | 30°C / 85°F | 12°C / 54°F | 0 mm | 62% | 12% |
| August | 30°C / 86°F | 13°C / 55°F | 0 mm | 63% | 14% |
| September | 30°C / 85°F | 13°C / 55°F | 3 mm | 61% | 16% |
| October | 26°C / 79°F | 11°C / 51°F | 21 mm | 60% | 23% |
| November | 19°C / 66°F | 7°C / 45°F | 57 mm | 71% | 39% |
| December | 14°C / 58°F | 4°C / 39°F | 90 mm | 79% | 46% |
What to pack for September
- Light, breathable clothing (cotton or linen)
- A sun hat and high-SPF sunscreen
- A refillable water bottle
- An extra layer — evenings are noticeably cooler than afternoons
- Sunglasses
Is September a good time to visit San Jose?
Compare the months in the chart above to find your ideal window.
Best time to visit San Jose →Other United States cities in September
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San Jose weather in September. WeatherCompare, 2026 (NASA POWER / ERA5, 2011–2020 monthly averages). https://weathercompare.eu/weather/usa/san-jose-usa/september
<a href="https://weathercompare.eu/weather/usa/san-jose-usa/september">San Jose weather in September</a> (WeatherCompare)
<iframe src="https://weathercompare.eu/embed/usa/san-jose-usa" width="300" height="160" style="border:0;border-radius:12px" loading="lazy" title="San Jose weather in September"></iframe> <p style="font-size:12px"><a href="https://weathercompare.eu/weather/usa/san-jose-usa/september">San Jose weather in September</a> – WeatherCompare</p>
San Jose in September: quick answers
Is September a good time to visit San Jose?
September is a reasonable time for San Jose: highs around 30°C and about 3 mm of rain, though not one of the three best months.
How warm is San Jose in September?
Average highs are about 30°C (85°F) and average lows about 13°C (55°F), based on 10 years of daily data.
Does it rain a lot in San Jose in September?
San Jose typically gets around 3 mm of rain in September — very dry.
Figures are long-term averages for the area around San Jose (NASA POWER / ERA5, 2011–2020), not a forecast for a specific year. For upcoming days, see the live multi-source forecast.