September weather forecast
Sebastopol, CA

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Weather in September

September, the first month of the autumn in Sebastopol, is still a warm month, with temperature in the range of an average high of 79°F (26.1°C) and an average low of 54.7°F (12.6°C).

Temperature

On the advent of September, Sebastopol's average high-temperature exhibits a minor adjustment to a still warm 79°F (26.1°C) from August's 79.7°F (26.5°C). September witnesses a substantial contrast between the daytime highs and the average low of 54.7°F (12.6°C).

Humidity

The least humid month is September, with an average relative humidity of 63%.

Rainfall

In Sebastopol, during September, the rain falls for 2.8 days and regularly aggregates up to 0.12" (3mm) of precipitation. Throughout the year, there are 72.8 rainfall days, and 12.01" (305mm) of precipitation is accumulated.

Daylight

In September, the average length of the day is 12h and 25min.
On the first day of September, sunrise is at 6:41 am and sunset at 7:40 pm. On the last day of the month, sunrise is at 7:06 am and sunset at 6:55 pm PDT.

Sunshine

In September, the average sunshine is 11h.

UV index

In Sebastopol, California, the average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV rays for the ordinary person.
Note: In September, the average maximum UV index of 5 translates into the following recommendations:
Undertake precautions - Obligation exists to protect against skin and eye damage. The intensity of the Sun's UV radiation during midday suggests reducing time spent outdoors. For a sun-safe wardrobe, go for clothes that are tightly woven and generously sized.
Updated: Aug 16, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the usual temperature for Sebastopol in September?

During September, Sebastopol experiences an average high-temperature of 79°F (26.1°C) and a low-temperature of 54.7°F (12.6°C).

What is the least humid month?

The least humid month is September, with an average relative humidity of 63%.

What is the average humidity in September?

In Sebastopol, the average relative humidity in September is 63%.

How many days does it rain in September?

In September, in Sebastopol, the rain falls for 2.8 days. Throughout September, 0.12" (3mm) of precipitation is accumulated.

How many hours of daylight does Sebastopol have in September?

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

When is the sunrise / sunset in September?

On the first day of September, sunrise is at 6:41 am and sunset at 7:40 pm. On the last day of the month, sunrise is at 7:06 am and sunset at 6:55 pm PDT.

How many hours of sunshine does Sebastopol have in September?

In Sebastopol, the average sunshine duration in September is 11h.

What is the UV index reading in September in Sebastopol?

The average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a moderate health threat from unprotected exposure to 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
Sebastopol, CA

Average temperature in September - Sebastopol, CA
  • Average high temperature in September: 79°F

The warmest month (with the highest average high temperature) is August (79.7°F).
The month with the lowest average high temperature is December (55.6°F).

  • Average low temperature in September: 54.7°F

The months with the highest average low temperature are August and September (54.7°F).
The coldest month (with the lowest average low temperature) is December (41.9°F).

Average pressure in September
Sebastopol, CA

Average pressure in September - Sebastopol, 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
Sebastopol, CA

Average wind speed in September - Sebastopol, CA
  • Average wind speed in September: 5.2mph

The windiest month (with the highest average wind speed) is May (7.1mph).
The calmest month (with the lowest average wind speed) is November (4.9mph).

Average humidity in September
Sebastopol, CA

Average humidity in September - Sebastopol, CA
  • Average humidity in September: 63%

The month with the highest relative humidity is March (77%).
The month with the lowest relative humidity is September (63%).

Average rainfall in September
Sebastopol, CA

Average rainfall in September - Sebastopol, CA
  • Average rainfall in September: 0.12"

The wettest month (with the highest rainfall) is February (2.64").
The driest months (with the least rainfall) are July and August (0.04").

Average rainfall days in September
Sebastopol, CA

Average rainfall days in September - Sebastopol, CA
  • Average rainfall days in September: 2.8 days

The month with the highest number of rainy days is March (12.6 days).
The month with the least rainy days is August (0.8 days).

Average daylight in September /
Average sunshine in September
Sebastopol, CA

Average daylight in September / Average sunshine in September - Sebastopol, 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 30min).

  • Average sunshine in September: 11h and 0min

The month with the most sunshine is July (Average sunshine: 11h and 54min).
The month with the least sunshine is December (Average sunshine: 5h and 42min).

Average sunshine days in September
Sebastopol, CA

Average sunshine days in September - Sebastopol, CA
  • Average sunshine days in September: 26.5 days

The month with the most sunshine days is July (27.2 days).
The month with the least sunshine days is March (17.1 days).

Average UV index in September
Sebastopol, CA

Average UV index in September - Sebastopol, 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
Sebastopol, CA

Average cloud cover in September - Sebastopol, CA
  • Average cloud cover in September: 10

The month with the most cloud cover is March (Cloud cover 39).
The month with the least cloud cover is July (Cloud cover 9).

Average visibility in September
Sebastopol, CA

Average visibility in September - Sebastopol, 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).

Sebastopol, California, USA

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