September weather forecast and climate
Brentwood, CA

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

Weather in September

September, the first month of the autumn, in Brentwood, is still a warm month, with average temperature fluctuating between 85.3°F (29.6°C) and 57.7°F (14.3°C).

Temperature

In Brentwood, 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 Brentwood, is 57.7°F (14.3°C).

Heat index

The average heat index in September is evaluated at a hot 87.4°F (30.8°C). Constant exposure and activity lead to possible fatigue. Prolonged exercise may result in heat cramps.
Note that heat index values are valued for light wind and location in the shade. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature', 'real feel', 'feels like', or 'apparent temperature', is what the temperature feels like to the human body when the air temperature is combined with the relative humidity. This effect is individual, with diverse people perceiving weather differently for numerous reasons (clothing, metabolic differences, pregnancy), and activity. Be aware that direct exposure to sunlight increases heat impact, and may raise the heat index additionally, by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.

Humidity

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

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 snow does not fall in January through November.

Daylight

The average length of the day in Brentwood, California, is 12.4h.

Sunshine

In September, the average sunshine is 11.2h.

UV index

In Brentwood, the average daily maximum UV index is 5. A UV Index estimate of 3 to 5 represents a medium health hazard from the exposure to the Sun's UV radiation for the ordinary person.
Note: In September, the average maximum UV index of 5 translate into the following recommendations:
Take precautions. Light skin individuals may get burned in less than 30 minutes. 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 temperature in September in Brentwood?

The average high-temperature, in September, in Brentwood, is 85.3°F (29.6°C), while the average low-temperature is 57.7°F (14.3°C). The average heat index (a.k.a. 'real feel', 'apparent temperature'), that represents influence of the relative humidity to air temperaure, in September is evaluated at 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, during September, the rain falls for 1.3 days and regularly aggregates up to 0.08" (2mm) of precipitation.

When it does not snow in Brentwood?

January through November are months without snowfall in Brentwood, California.

What is the average length of the day in September in Brentwood?

In Brentwood, the average length of the day in September is 12.4h.

How many hours of sunshine does Brentwood have in September?

The average sunshine in September in Brentwood, California, is 11.2h.

How high is the UV index in September in Brentwood?

In September, the average daily maximum UV index in Brentwood is 5. A UV Index reading of 3 to 5 represents a medium health risk from unprotected exposure to the UV radiation.

Average temperature in September
Brentwood, CA

Average temperature in September - Brentwood, CA
  • Average high temperature in September: 29.6°C

The warmest month (with the highest average high temperature) is July (31.4°C).
The month with the lowest average high temperature is December (12.8°C).

  • Average low temperature in September: 14.3°C

The month with the highest average low temperature is September (14.3°C).
The coldest month (with the lowest average low temperature) is January (5.3°C).

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Average pressure in September
Brentwood, CA

Average pressure in September - Brentwood, CA
  • Average pressure in September: 1013.1mbar

The month with the highest atmospheric pressure is January (1020.6mbar).
The month with the lowest atmospheric pressure is June (1012.9mbar).

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Average wind speed in September
Brentwood, CA

Average wind speed in September - Brentwood, CA
  • Average wind speed in September: 9.9km/h

The windiest month (with the highest average wind speed) is June (12.5km/h).
The calmest months (with the lowest average wind speed) are January and November (7.3km/h).

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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: 2mm

The wettest month (with the highest rainfall) is February (53mm).
The driest months (with the least rainfall) are July and August (1mm).

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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).
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: 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: 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

Months with the highest UV index are June, July and August (UV index 6).
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

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: 10km

Months with the highest visibility are May, June, July, August, September, October and November (10km).
Months with the lowest visibility are January, February, March, April and December (9km).

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