September weather forecast and climate
Westmont, CA

Weather in September

September, the first month of the autumn, in Westmont, is also a moderately hot month, with temperature in the range of an average low of 64.2°F (17.9°C) and an average high of 79.7°F (26.5°C).

Temperature

In September, the average high-temperature is essentially the same as in August - a still moderately hot 79.7°F (26.5°C). In September, the average low-temperature is 64.2°F (17.9°C).

Humidity

The average relative humidity in Westmont is 62%.

Rainfall

In Westmont, California, during September, the rain falls for 3.2 days and regularly aggregates up to 0.24" (6mm) of precipitation. In Westmont, California, during the entire year, the rain falls for 47.6 days and collects up to 7.24" (184mm) of precipitation.

Daylight

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

Sunshine

In September, the average sunshine in Westmont is 10.5h.

UV index

Months with the highest UV index in Westmont are June through September, with an average maximum UV index of 6. A UV Index of 6 to 7 symbolizes a high threat to health from unsafe exposure to the UV radiation for ordinary individuals.
Note: In September, the average maximum UV index of 6 translate into the following recommendations:
Take precautions and utilize sun safety practices. Protection against the skin and eye damage is required. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. 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 Westmont?

The average high-temperature, in September, is 79.7°F (26.5°C), while the average low-temperature is 64.2°F (17.9°C).

What is the average humidity in September in Westmont?

In September, the average relative humidity is 62%.

How many days does it rain in September in Westmont?

In Westmont, during September, the rain falls for 3.2 days and regularly aggregates up to 0.24" (6mm) of precipitation.

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

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

How many hours of sunshine does Westmont have in September?

In Westmont, California, the average sunshine in September is 10.5h.

What are the months with the highest UV index in Westmont?

Months with the highest UV index in Westmont, California, are June through September, with an average maximum UV index of 6.

What is the UV index intensity in September in Westmont?

The average daily maximum UV index in September is 6. A UV Index estimate of 6 to 7 represents a high health threat from the exposure to the Sun's UV radiation.

Average temperature in September
Westmont, CA

Average temperature in September - Westmont, CA
  • Average high temperature in September: 79.7°F

The warmest month (with the highest average high temperature) is August (80.2°F).
The month with the lowest average high temperature is December (64°F).

  • Average low temperature in September: 64.2°F

The month with the highest average low temperature is August (64.9°F).
The coldest month (with the lowest average low temperature) is February (51.1°F).

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Average pressure in September
Westmont, CA

Average pressure in September - Westmont, CA
  • Average pressure in September: 29.9"

The month with the highest atmospheric pressure is January (30.1").
The month with the lowest atmospheric pressure is June (29.89").

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Average wind speed in September
Westmont, CA

Average wind speed in September - Westmont, CA
  • Average wind speed in September: 4.9mph

The windiest month (with the highest average wind speed) is April (6.4mph).
The calmest month (with the lowest average wind speed) is September (4.9mph).

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Average humidity in September
Westmont, CA

Average humidity in September - Westmont, CA
  • Average humidity in September: 62%

The month with the highest relative humidity is June (70%).
The month with the lowest relative humidity is November (54%).

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Average rainfall in September
Westmont, CA

Average rainfall in September - Westmont, CA
  • Average rainfall in September: 0.24"

The wettest month (with the highest rainfall) is January (1.42").
The driest month (with the least rainfall) is June (0.08").

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Average rainfall days in September
Westmont, CA

Average rainfall days in September - Westmont, CA
  • Average rainfall days in September: 3.2 days

The month with the highest number of rainy days is March (6.5 days).
The month with the least rainy days is June (1.7 days).

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

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

The month with the longest days is June (Average daylight: 14.4h).
The month with the shortest days is December (Average daylight: 9.9h).

  • Average sunshine in September: 10.5h

Months with the most sunshine are July and August (Average sunshine: 11.9h).
The month with the least sunshine is December (Average sunshine: 6.7h).

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Average sunshine days in September
Westmont, CA

Average sunshine days in September - Westmont, CA
  • Average sunshine days in September: 23.4 days

The month with the most sunshine days is October (25.5 days).
The month with the least sunshine days is June (21.4 days).

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Average UV index in September
Westmont, CA

Average UV index in September - Westmont, CA
  • Average UV index in September: 6

Months with the highest UV index are June, July, August and September (UV index 6).
Months with the lowest UV index are January, February, November and December (UV index 4).

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Average cloud cover in September
Westmont, CA

Average cloud cover in September - Westmont, CA
  • Average cloud cover in September: 11

Months with the most cloud cover are March and December (Cloud cover 22).
The month with the least cloud cover is August (Cloud cover 7).

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Average visibility in September
Westmont, CA

Average visibility in September - Westmont, 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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