The highest day temperature in September 2025 was 90°F. The lowest night temperature was 78°F. The average values for day and night temperatures during September were 87.8°F и 80.2°F respectivly.

The average sea surface temperature in September 2025 for Port of San Jose was 89.6°F. The maximum and minimum values were 88.6°F and 90.4°F respectively.

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

Precipitation total in September for Port of San Jose is 4.0 in. It makes september one of the most rainy months of the year.

The average wind speed in September is 5.7 mph. This value is relatively stable throughout the year.

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 Port of San Jose in September is 5.0 hours.