September weather forecastSan Anselmo, CA
September
Weather in September
As September arrives, San Anselmo gets a respite from the peak summer heat as temperature highs decline to 72.3°F (22.4°C). It ushers in slightly cooler days and nights, painting a pleasant climate canvas. This is accompanied by the least cloud cover observed in the year at 19%, making for clear sky days. With rain levels consistent at 0.04" (1mm), similar to previous months, it grants continuity to the prolonged dry spell. The wind speed slows further, marking a transition from the summer to fall.Temperature
The average temperatures reach their apex in September, averaging 72.3°F (22.4°C) at the high end and 56.1°F (13.4°C) at the low end.Humidity
In San Anselmo, the average relative humidity in September is 71%.Rainfall
The months with the least rainfall in San Anselmo are June through September Rain falls for 1.7 days and accumulates 0.04" (1mm) of rain.Daylight
In September, the average length of the day is 12h and 25min.On the first day of the month, sunrise is at 6:40 am and sunset at 7:39 pm. On the last day of September, in San Anselmo, sunrise is at 7:05 am and sunset at 6:54 pm PDT.
Sunshine
In September, the average sunshine is 10.4h.UV index
The months with the highest UV index are April, June through September, with an average maximum UV index of 5. A UV Index reading of 3 to 5 represents a medium vulnerability from unprotected exposure to Sun's UV rays for the average person.Note: In September, the maximum UV index of 5 translates into these guidelines:
Act with care - The need to guard against sun damage is communicated. Direct exposure to the Sun's intense radiation around midday should be avoided for health reasons. To best shield against UV radiation, choose sun-safe garments and dependable sunglasses.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
San Anselmo, CA
- Average high temperature in September: 72.3°F
The warmest month (with the highest average high temperature) is September (72.3°F).
The month with the lowest average high temperature is December (55.4°F).
- Average low temperature in September: 56.1°F
The month with the highest average low temperature is September (56.1°F).
The coldest month (with the lowest average low temperature) is December (45.3°F).
Average pressure in September
San Anselmo, 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 Anselmo, CA
- Average wind speed in September: 5.9mph
The windiest month (with the highest average wind speed) is May (7.8mph).
The calmest months (with the lowest average wind speed) are October and November (5.5mph).
Average humidity in September
San Anselmo, CA
- Average humidity in September: 71%
The month with the highest relative humidity is March (77%).
The month with the lowest relative humidity is October (68%).
Average rainfall in September
San Anselmo, CA
- Average rainfall in September: 0.04"
The wettest month (with the highest rainfall) is February (0.87").
The driest months (with the least rainfall) are June, July, August and September (0.04").
Average rainfall days in September
San Anselmo, CA
- Average rainfall days in September: 1.7 days
The month with the highest number of rainy days is March (8.8 days).
The months with the least rainy days are June and August (1.2 days).
Average daylight in September /
Average sunshine in September
San Anselmo, 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 24min
The month with the most sunshine is July (Average sunshine: 11h and 12min).
The month with the least sunshine is December (Average sunshine: 5h and 30min).
Average sunshine days in September
San Anselmo, CA
- Average sunshine days in September: 26 days
The month with the most sunshine days is June (26.4 days).
The month with the least sunshine days is March (20.7 days).
Average UV index in September
San Anselmo, CA
- Average UV index in September: 5
The months with the highest UV index are April, 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
San Anselmo, CA
- Average cloud cover in September: 19
The month with the most cloud cover is March (Cloud cover 39).
The month with the least cloud cover is September (Cloud cover 19).
Average visibility in September
San Anselmo, 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).
