Weather in San Jose in September 2025
Average weather
Average temperature in San Jose in September
The expected average maximum temperature in September is +27°C with a maximum of +31°C and a minimum of +11°C.
The average maximum temperature goes down 20% by the end of the month, compared with the beginning of the month, from +26°C to +22°C.
Is San Jose warm or cold in September?
San Jose is typically warm in September.
Maximum temperatures go down compared to the previous month from +28°C to +27°C. The minimum temperature also goes up from +15°C to +15°C.
It’s generally warm, but pack a long-sleeve shirt for evenings.
September is one of the warmest months in San Jose, here is the comparison with other months:
Climate in San Jose in September
| August | September | October | ||||
|---|---|---|---|---|---|---|
| Avg. temperature | ||||||
| +28°C | +27°C | +24°C | ||||
| Min. temperature | ||||||
| +10°C | +9°C | +5°C | ||||
| Max. temperature | ||||||
| +40°C | +43°C | +39°C | ||||
| Rainfall | ||||||
| 10 mm | 6 mm | 28 mm | ||||
| Wind | ||||||
| 2 m/s | 2 m/s | 1 m/s | ||||
| Humidity | ||||||
| 66% | 64% | 64% | ||||
| Air pressure | ||||||
| 1013 HPa | 1012 HPa | 1015 HPa | ||||
| Sunny days | ||||||
| 15 | 14 | 13 | ||||
| Cloudy days | ||||||
| 15 | 14 | 13 | ||||
| Rainy days | ||||||
| 1 | 2 | 5 | ||||
| Snowy days | ||||||
| 0 | 0 | 0 | ||||
September weather is still as great as in August. It’s getting colder in September. From +28°C in the day, the average maximum temperature lowers to +27°C. As September arrives, the amount of rainfall goes down. On average, the rainfall volume decreases from 10 mm to 6 mm. It feels drier, as humidity decreases from 66% to 64%. The average wind speed doesn’t change much during September, staying around 2 m/s. The days becoming less sunny, going from 15 sunny days in August to 14 in September.
Next month (October) brings a further decline in the weather.
Wind
The average wind speed is 8 m/s getting up to 15 m/s which is quite strong. The wind will cause branches to move and ground debris to fly around.
The average wind speed in San Jose is gradually decreasing during September, going from 12 m/s to 11 m/s over the course of the month.
Rain
How was the weather last September in San Jose?
Climate Change over Years
The climate in San Jose in September has not changed much over the last 43 years.
The average temperature was the lowest in 1982 (+20°C) and the highest in 2024 (+24°C). The driest year was 2013 with only 147 mm of rainfall, and the wettest year was 2020 with 4306 mm.
FAQ
Is September a good time to visit San Jose?
Can you sunbathe in San Jose in September?
Is San Jose rainy in September?
Is it sunny in San Jose in September?
Other cities in USA
Monthly weather in San Jose
Source of the data
For this page, we’ve looked at the typical weather in San Jose, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.
