September weather forecast and climate
San Geronimo, CA

Weather in September

The first month of the autumn, September, is still a pleasant month in San Geronimo, California, with average temperature varying between 70.9°F (21.6°C) and 56.3°F (13.5°C).

Temperature

With an average high-temperature of 70.9°F (21.6°C) and an average low-temperature of 56.3°F (13.5°C), September is the warmest month.

Humidity

In San Geronimo, the average relative humidity is 73%.

Rainfall

In September, in San Geronimo, California, the rain falls for 3.4 days. Throughout September, 0.12" (3mm) of precipitation is accumulated. Throughout the year, in San Geronimo, there are 80.3 rainfall days, and 15.98" (406mm) of precipitation is accumulated.

Snowfall

January through November are months without snowfall in San Geronimo.

Daylight

The average length of the day in September is 12.4h.

Sunshine

The average sunshine in September is 10.5h.

UV index

June through September, with an average maximum UV index of 5, are months with the highest UV index in San Geronimo. A UV Index reading of 3 to 5 represents a medium health hazard from unsafe exposure to the UV radiation for ordinary individuals.
Note: The average daily UV index of 5 transform into the following instructions:
Take precautions - Protection against sunburn is recommended. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.
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FAQ

What is the warmest month in San Geronimo?

With an average high-temperature of 70.9°F (21.6°C) and an average low-temperature of 56.3°F (13.5°C), September is the warmest month in San Geronimo.

What is the temperature in September in San Geronimo?

In September, the average high-temperature is 70.9°F (21.6°C), and the average low-temperature is 56.3°F (13.5°C).

What is the average humidity in September in San Geronimo?

In September, the average relative humidity in San Geronimo, California, is 73%.

How many days does it rain in September in San Geronimo?

In San Geronimo, in September, during 3.4 rainfall days, 0.12" (3mm) of precipitation is typically accumulated.

When it does not snow in San Geronimo?

In San Geronimo, California, snow does not fall in January through November.

What is the average length of the day in September in San Geronimo?

The average length of the day in September is 12.4h.

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

In San Geronimo, the average sunshine in September is 10.5h.

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

Months with the highest UV index in San Geronimo are June through September, with an average maximum UV index of 5.

What is the UV index reading in September in San Geronimo?

In September, the average daily maximum UV index in San Geronimo is 5. A UV Index value of 3 to 5 symbolizes a moderate vulnerability from the exposure to the Sun's UV radiation.

Average temperature in September
San Geronimo, CA

Average temperature in September - San Geronimo, CA
  • Average high temperature in September: 70.9°F

The warmest month (with the highest average high temperature) is September (70.9°F).
The month with the lowest average high temperature is December (55.2°F).

  • Average low temperature in September: 56.3°F

The month with the highest average low temperature is September (56.3°F).
The coldest month (with the lowest average low temperature) is December (46°F).

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Average pressure in September
San Geronimo, CA

Average pressure in September - San Geronimo, CA
  • Average pressure in September: 29.92"

The month with the highest atmospheric pressure is January (30.13").
Months with the lowest atmospheric pressure are June, August and September (29.92").

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Average wind speed in September
San Geronimo, CA

Average wind speed in September - San Geronimo, CA
  • Average wind speed in September: 6.3mph

The windiest months (with the highest average wind speed) are April and May (8.3mph).
The calmest month (with the lowest average wind speed) is November (5.9mph).

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Average humidity in September
San Geronimo, CA

Average humidity in September - San Geronimo, CA
  • Average humidity in September: 73%

The month with the highest relative humidity is August (78%).
The month with the lowest relative humidity is October (69%).

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Average rainfall in September
San Geronimo, CA

Average rainfall in September - San Geronimo, CA
  • Average rainfall in September: 0.12"

The wettest month (with the highest rainfall) is February (3.43").
The driest months (with the least rainfall) are July and August (0.08").

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Average rainfall days in September
San Geronimo, CA

Average rainfall days in September - San Geronimo, CA
  • Average rainfall days in September: 3.4 days

The month with the highest number of rainy days is March (12.8 days).
The month with the least rainy days is July (2.3 days).

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Average snowfall days in September
San Geronimo, CA

Average snowfall days in September - San Geronimo, CA
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is December (0.1 days).
Months with the least snowfall days are January, February, March, April, May, June, July, August, September, October and November (0 days).

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Average daylight in September /
Average sunshine in September
San Geronimo, CA

Average daylight in September / Average sunshine in September - San Geronimo, CA
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 14.8h).
The month with the shortest days is December (Average daylight: 9.6h).

  • Average sunshine in September: 10.5h

The month with the most sunshine is July (Average sunshine: 11.2h).
The month with the least sunshine is December (Average sunshine: 5.6h).

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Average sunshine days in September
San Geronimo, CA

Average sunshine days in September - San Geronimo, CA
  • Average sunshine days in September: 24.1 days

Months with the most sunshine days are June and July (24.8 days).
The month with the least sunshine days is March (16.6 days).

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Average UV index in September
San Geronimo, CA

Average UV index in September - San Geronimo, CA
  • Average UV index in September: 5

Months with the highest UV index are June, July, August and September (UV index 5).
Months with the lowest UV index are February, November and December (UV index 3).

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Average cloud cover in September
San Geronimo, CA

Average cloud cover in September - San Geronimo, 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).

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Average visibility in September
San Geronimo, CA

Average visibility in September - San Geronimo, CA
  • Average visibility in September: 6mi

Months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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