The highest day temperature in September 2026 was 75°F. The lowest night temperature was 60°F. The average values for day and night temperatures during September were 71.7°F и 61.7°F respectivly.

The average sea surface temperature in September 2026 for San Jose was 90.5°F. The maximum and minimum values were 89.6°F and 91.6°F respectively.

Most of the days in September are gloomy but you can also expect sunny days.

Precipitation total in September for San Jose is 21.3 in. It makes september one of the most rainy months of the year.

The average wind speed in September is 2.6 mph. It makes September the most windless month of the year for San Jose.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for San Jose in September is 4.5 hours.