September weather forecast
San Anselmo, CA

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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.
Updated: Jun 17, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the hottest time of year?

In San Anselmo, September records the average highest temperatures, peaking at 72.3°F (22.4°C) and reaching a low of 56.1°F (13.4°C).

What are September temperatures?

The average high-temperature, in September, in San Anselmo, is 72.3°F (22.4°C), while the average low-temperature is 56.1°F (13.4°C).

What is the average humidity in September?

In September, the average relative humidity is 71%.

What is the driest month?

June through September are months with the least rain when the rain falls for 1.7 days and typically aggregates up to 0.04" (1mm) of rain.

How much does it rain in San Anselmo in September?

In San Anselmo, in September, it is raining for 1.7 days, with typically 0.04" (1mm) of accumulated precipitation.

How many hours of daylight does San Anselmo have in September?

In San Anselmo, the average day length in September is 12h and 25min.

When are sunrise and sunset in September in San Anselmo?

On the first day of September, sunrise is at 6:40 am and sunset at 7:39 pm. On the last day of the month, sunrise is at 7:05 am and sunset at 6:54 pm PDT.

How many hours of sunshine does San Anselmo have in September?

In San Anselmo, the average sunshine duration in September is 10.4h.

What are the months with the highest UV index in San Anselmo?

April, June through September, with an average maximum UV index of 5, are months with the highest UV index.

How high is the UV index in September?

In San Anselmo, the average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a moderate health threat from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
San Anselmo, CA

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 - 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 - 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 - 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 - 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 - 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 / Average sunshine in September - San Anselmo, CA
  • Average daylight in September: 12h and 2min

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 2min

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 - 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 - 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 - 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 - 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).

San Anselmo, California, USA

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