September weather forecastRichmond, CA
September
Weather in September
The first month of the autumn, September, is also a moderately hot month in Richmond, California, with an average temperature fluctuating between 75.7°F (24.3°C) and 56.5°F (13.6°C).Temperature
In Richmond, September is the month with the highest recorded average temperatures, measuring a high of 75.7°F (24.3°C) and a low of 56.5°F (13.6°C).Humidity
In Richmond, the average relative humidity in September is 66%.Rainfall
The months with the least rainfall in Richmond are June through September Rain falls for 2.5 days and accumulates 0.08" (2mm) of rain.Ocean temperature
September is the month with the warmest seawater in Richmond, with an average ocean temperature of 57.4°F (14.1°C).Note: Entering waters of 57.4°F (14.1°C) is life-endangering. A mere moment in 55.4°F (13°C) waters feels piercing cold, and below 50°F (10°C) it can lead to immediate cold shock and cessation of breathing control, depending on body resilience.
Daylight
In September, the average length of the day in Richmond, California, is 12h and 25min.On the first day of the month, sunrise is at 6:40 am and sunset at 7:38 pm. On the last day of September, sunrise is at 7:04 am and sunset at 6:53 pm PDT.
Sunshine
In Richmond, California, the average sunshine in September is 10.8h.UV index
The months with the highest UV index in Richmond, California, are April through September, with an average maximum UV index of 5. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for the ordinary person.Note: The daily high UV index of 5 during September translates into the following recommendations:
Take precautions - Protection against sun damage is advised. To guard against the harmful effects of the Sun, minimize exposure during midday. In bright sunlight, prioritize sunglasses that grant protection from UVA and UVB radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Richmond, CA
- Average high temperature in September: 75.7°F
The warmest month (with the highest average high temperature) is September (75.7°F).
The month with the lowest average high temperature is December (55.6°F).
- Average low temperature in September: 56.5°F
The month with the highest average low temperature is September (56.5°F).
The coldest month (with the lowest average low temperature) is January (44.8°F).
Average pressure in September
Richmond, 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
Richmond, CA
- Average wind speed in September: 5.7mph
The windiest month (with the highest average wind speed) is May (7.5mph).
The calmest month (with the lowest average wind speed) is November (5.1mph).
Average humidity in September
Richmond, CA
- Average humidity in September: 66%
The month with the highest relative humidity is March (75%).
The month with the lowest relative humidity is October (65%).
Average rainfall in September
Richmond, CA
- Average rainfall in September: 0.08"
The wettest month (with the highest rainfall) is February (1.38").
The driest months (with the least rainfall) are June, July, August and September (0.08").
Average rainfall days in September
Richmond, CA
- Average rainfall days in September: 2.5 days
The month with the highest number of rainy days is March (10.8 days).
The month with the least rainy days is June (2 days).
Average sea temperature in September
Richmond, CA
- Average sea temperature in September: 57.3°F
The best month for swimming (with the highest average sea temperature) is September (57.3°F).
The coldest months (with the lowest average sea temperature) are April and June (53°F).
Average daylight in September /
Average sunshine in September
Richmond, 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: 10h and 48min
The month with the most sunshine is July (Average sunshine: 11h and 48min).
The month with the least sunshine is December (Average sunshine: 5h and 42min).
Average sunshine days in September
Richmond, CA
- Average sunshine days in September: 24.5 days
The month with the most sunshine days is July (24.9 days).
The month with the least sunshine days is March (18.4 days).
Average UV index in September
Richmond, CA
- Average UV index in September: 5
The months with the highest UV index are April, May, June, July, August and September (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in September
Richmond, CA
- Average cloud cover in September: 15
The month with the most cloud cover is March (Cloud cover 37).
The month with the least cloud cover is July (Cloud cover 14).
Average visibility in September
Richmond, 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).
