September weather forecast
Brentwood, CA

Scenic and organized home community in Brentwood City, California
Scenic and organized home community in Brentwood City, California

Weather in September

The first month of the autumn, September, is also a moderately hot month in Brentwood, California, with temperature in the range of an average high of 85.3°F (29.6°C) and an average low of 57.7°F (14.3°C).

Temperature

In September, the average high-temperature is essentially the same as in August - a moderately hot 85.3°F (29.6°C). The average low-temperature, in September, is 57.7°F (14.3°C).

Heat index

The average heat index in September is calculated to be a tropical 87.4°F (30.8°C). Exhaustion is likely with prolonged exposure and activity. Sustaining activity may result in heat cramps.
Note that heat index values are valued for light wind and location in the shade. With exposure to direct sunlight, the heat index may be increased by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel', 'feels like', 'apparent temperature', or 'felt air temperature', is a calculated temperature value of how hot it feels when the moisture in the air is factored in. Additional factors like activity, wind, pregnancy, and differences in body mass, height, and shape affect individual temperature impact. Be aware that direct exposure to sunlight increases heat impact and may raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.

Humidity

With an average relative humidity of 52%, September is the least humid month in Brentwood.

Rainfall

In Brentwood, during September, the rain falls for 1.3 days and regularly aggregates up to 0.08" (2mm) of precipitation. Throughout the year, there are 62 rainfall days, and 10.16" (258mm) of precipitation is accumulated.

Snowfall

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

Daylight

The average length of the day in September is 12h and 25min.
On the first day of the month, sunrise is at 6:36 am and sunset at 7:36 pm. On the last day of September, sunrise is at 7:01 am and sunset at 6:51 pm PDT.

Sunshine

In Brentwood, the average sunshine in September is 11.2h.

UV index

The average daily maximum UV index in September is 5. A UV Index estimate of 3 to 5 represents a medium vulnerability from unsafe exposure to UV radiation for ordinary individuals.
Note: The daily maximum UV index of 5 in September interpret into the following advice:
Take precautions - Protection against sun damage is advised. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun.
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FAQ

What is the temperature in September in Brentwood?

In Brentwood, in September, the average high-temperature is 85.3°F (29.6°C), and the average low-temperature is 57.7°F (14.3°C). In September, the average heat index (a.k.a. 'apparent temperature', 'feels like'), which factors the actual air temperature with the relative humidity, is calculated to be 87.4°F (30.8°C).

What is the least humid month in Brentwood?

September is the least humid month in Brentwood, with an average relative humidity of 52%.

What is the average humidity in September in Brentwood?

In September, the average relative humidity is 52%.

How many days does it rain in September in Brentwood?

In Brentwood, California, in September, during 1.3 rainfall days, 0.08" (2mm) of precipitation is typically accumulated.

When it does not snow in Brentwood?

January through November are months without snowfall in Brentwood.

How many hours of daylight does Brentwood have in September?

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

When are sunrise and sunset in September in Brentwood?

On the first day of September in Brentwood, California, sunrise is at 6:36 am and sunset at 7:36 pm. On the last day of the month, sunrise is at 7:01 am and sunset at 6:51 pm PDT.

How many hours of sunshine does Brentwood have in September?

In Brentwood, California, the average sunshine duration in September is 11.2h.

What is the UV index reading in September in Brentwood?

In September, the average daily maximum UV index in Brentwood, California, is 5. A UV Index estimate of 3 to 5 represents a medium hazard to health from exposure to the Sun's UV radiation.

Average temperature in September
Brentwood, CA

Average temperature in September - Brentwood, CA
  • Average high temperature in September: 85.3°F

The warmest month (with the highest average high temperature) is July (88.5°F).
The month with the lowest average high temperature is December (55°F).

  • Average low temperature in September: 57.7°F

The month with the highest average low temperature is September (57.7°F).
The coldest month (with the lowest average low temperature) is January (41.5°F).

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Average pressure in September
Brentwood, CA

Average pressure in September - Brentwood, CA
  • Average pressure in September: 29.92"Hg

The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).

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Average wind speed in September
Brentwood, CA

Average wind speed in September - Brentwood, CA
  • Average wind speed in September: 6.2mph

The windiest month (with the highest average wind speed) is June (7.8mph).
The calmest months (with the lowest average wind speed) are January and November (4.5mph).

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Average humidity in September
Brentwood, CA

Average humidity in September - Brentwood, CA
  • Average humidity in September: 52%

The month with the highest relative humidity is January (74%).
The month with the lowest relative humidity is September (52%).

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Average rainfall in September
Brentwood, CA

Average rainfall in September - Brentwood, CA
  • Average rainfall in September: 0.08"

The wettest month (with the highest rainfall) is February (2.09").
The driest months (with the least rainfall) are July and August (0.04").

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Average rainfall days in September
Brentwood, CA

Average rainfall days in September - Brentwood, CA
  • Average rainfall days in September: 1.3 days

The month with the highest number of rainy days is March (12.3 days).
The month with the least rainy days is August (0.8 days).

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Average snowfall days in September
Brentwood, CA

Average snowfall days in September - Brentwood, CA
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is December (0.1 days).
The 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
Brentwood, CA

Average daylight in September / Average sunshine in September - Brentwood, CA
  • Average daylight in September: 12h and 25min

The month with the longest days is June (Average daylight: 14h and 45min).
The month with the shortest days is December (Average daylight: 9h and 35min).

  • Average sunshine in September: 11.2h

The month with the most sunshine is July (Average sunshine: 12.1h).
The month with the least sunshine is December (Average sunshine: 5.8h).

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Average sunshine days in September
Brentwood, CA

Average sunshine days in September - Brentwood, CA
  • Average sunshine days in September: 28.5 days

The month with the most sunshine days is August (29.8 days).
The month with the least sunshine days is March (17.7 days).

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Average UV index in September
Brentwood, CA

Average UV index in September - Brentwood, CA
  • Average UV index in September: 5

The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).

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Average cloud cover in September
Brentwood, CA

Average cloud cover in September - Brentwood, CA
  • Average cloud cover in September: 8

The months with the most cloud cover are March and December (Cloud cover 35).
The month with the least cloud cover is July (Cloud cover 5).

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Average visibility in September
Brentwood, CA

Average visibility in September - Brentwood, 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).

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