September weather forecastPort Costa, CA
September
Weather in September
The first month of the autumn, September, is also a moderately hot month in Port Costa, California, with an average temperature fluctuating between 56.3°F (13.5°C) and 80.1°F (26.7°C).Temperature
The highest point of temperatures falls in July and September, when the average high-temperature ascends to 80.1°F (26.7°C).Humidity
September and October, with an average relative humidity of 60%, are the least humid months.Rainfall
In Port Costa, in September, during 2.1 rainfall days, 0.08" (2mm) of precipitation is typically accumulated. In Port Costa, during the entire year, the rain falls for 56.9 days and collects up to 4.88" (124mm) 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 6:39 am and sunset at 7:37 pm. On the last day of September, sunrise is at 7:04 am and sunset at 6:52 pm PDT.
Sunshine
In Port Costa, California, the average sunshine in September is 11.1h.UV index
In September, the average daily maximum UV index is 5. A UV Index estimate of 3 to 5 represents a medium health hazard from unsafe exposure to UV radiation for the average person.Note: A typical high UV index of 5 in September suggests the following recommendations:
Ensure safety - Sun damage prevention is strongly urged. It's recommended to limit sun exposure when its radiation is at its peak during midday. Employ a hat with a wide brim for robust protection, cutting UV exposure by half.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Port Costa, CA
- Average high temperature in September: 80.1°F
The warmest months (with the highest average high temperature) are July and September (80.1°F).
The month with the lowest average high temperature is December (55.4°F).
- Average low temperature in September: 56.3°F
The month with the highest average low temperature is August (56.5°F).
The coldest month (with the lowest average low temperature) is January (43°F).
Average pressure in September
Port Costa, CA
- Average pressure in September: 29.92"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in September
Port Costa, CA
- Average wind speed in September: 5.5mph
The windiest month (with the highest average wind speed) is May (7.1mph).
The calmest month (with the lowest average wind speed) is November (4.6mph).
Average humidity in September
Port Costa, CA
- Average humidity in September: 60%
The month with the highest relative humidity is March (75%).
The months with the lowest relative humidity are September and October (60%).
Average rainfall in September
Port Costa, CA
- Average rainfall in September: 0.08"
The wettest month (with the highest rainfall) is February (1.14").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in September
Port Costa, CA
- Average rainfall days in September: 2.1 days
The month with the highest number of rainy days is March (10.2 days).
The month with the least rainy days is August (0.9 days).
Average daylight in September /
Average sunshine in September
Port Costa, CA
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in September: 11h and 6min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 42min).
Average sunshine days in September
Port Costa, CA
- Average sunshine days in September: 26 days
The month with the most sunshine days is July (27.2 days).
The month with the least sunshine days is March (18.8 days).
Average UV index in September
Port Costa, CA
- Average UV index in September: 5
The month with the highest UV index is June (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in September
Port Costa, CA
- Average cloud cover in September: 11
The month with the most cloud cover is March (Cloud cover 37).
The month with the least cloud cover is July (Cloud cover 9).
Average visibility in September
Port Costa, 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).
