September weather forecastSan Jose, CA
September
Weather in September
September weather in San Jose signifies the transition from summer to fall, bringing about a slight reduction in temperatures. Reflecting the change in the season, the daylight hours reduce to approximately 12.4 per day, yet the city enjoys a warm and dry climate. Akin to August, the city witnesses an average relative humidity of 60%. As the departure from summer begins, September sets a calm and warm prelude to the fall season.Temperature
The shift into September records an average high-temperature of a still moderately hot 79.7°F (26.5°C), subtly varied from August's 81.9°F (27.7°C). San Jose's September nights cool down significantly from the day's heat, to an average low-temperature of 55.6°F (13.1°C).Humidity
July and September, with an average relative humidity of 60%, are the least humid months.Rainfall
In San Jose, California, during September, the rain falls for 2.1 days and regularly aggregates up to 0.08" (2mm) of precipitation. In San Jose, California, during the entire year, the rain falls for 51.5 days and collects up to 4.06" (103mm) of precipitation.Daylight
In September, the average length of the day is 12h and 25min.On the first day of the month, sunrise is at 6:38 am and sunset at 7:35 pm. On the last day of September, sunrise is at 7:02 am and sunset at 6:51 pm PDT.
Sunshine
The average sunshine in September is 11.2h.UV index
In San Jose, the average daily maximum UV index in September is 5. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for ordinary individuals.Note: In September, an average UV index of 5 transforms into the following instructions:
Guard yourself - Avoiding sunburn is suggested. Midday Sun has the strongest UV rays, making it crucial to limit exposure and find shade. Consider a wide-brim hat essential for effective sun defense covering your face, neck, and eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
San Jose, CA
- Average high temperature in September: 79.7°F
The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is December (56.5°F).
- Average low temperature in September: 55.6°F
The month with the highest average low temperature is August (56.5°F).
The coldest month (with the lowest average low temperature) is December (43°F).
Average pressure in September
San Jose, CA
- Average pressure in September: 29.92"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.92"Hg).
Average wind speed in September
San Jose, CA
- Average wind speed in September: 4.4mph
The windiest months (with the highest average wind speed) are April and May (5.8mph).
The calmest months (with the lowest average wind speed) are September and October (4.4mph).
Average humidity in September
San Jose, CA
- Average humidity in September: 60%
The month with the highest relative humidity is March (73%).
The months with the lowest relative humidity are July and September (60%).
Average rainfall in September
San Jose, CA
- Average rainfall in September: 0.08"
The wettest month (with the highest rainfall) is March (0.83").
The driest months (with the least rainfall) are June, July and August (0.04").
Average rainfall days in September
San Jose, CA
- Average rainfall days in September: 2.1 days
The month with the highest number of rainy days is March (9.8 days).
The month with the least rainy days is August (0.4 days).
Average daylight in September /
Average sunshine in September
San Jose, CA
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in September: 11h and 12min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 6h and 0min).
Average sunshine days in September
San Jose, CA
- Average sunshine days in September: 26.8 days
The month with the most sunshine days is August (29.7 days).
The month with the least sunshine days is March (19.5 days).
Average UV index in September
San Jose, CA
- Average UV index in September: 5
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in September
San Jose, CA
- Average cloud cover in September: 10
The month with the most cloud cover is March (Cloud cover 35).
The month with the least cloud cover is July (Cloud cover 6).
Average visibility in September
San Jose, CA
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
