Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
September reports an average high-temperature of a still warm 79.7°F (26.5°C), slightly varied from August's 80.2°F (26.8°C). In September, Westmont's temperature tends to fall to an average low of 64.2°F (17.9°C) during the night.Humidity
In September, the average relative humidity is 62%.Rainfall
In Westmont, in September, it is raining for 3.2 days, with typically 0.24" (6mm) of accumulated precipitation. In Westmont, 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 is 12h and 22min.On the first day of September, sunrise is at 6:27 am and sunset at 7:18 pm. On the last day of the month, sunrise is at 6:47 am and sunset at 6:38 pm PDT.
Sunshine
The average sunshine in September is 10.5h.UV index
June through September, with an average maximum UV index of 6, are months with the highest UV index. A UV Index value of 6 to 7 symbolizes a high health risk from exposure to the Sun's UV rays for the average person.Note: In September, the UV index of 6 transforms into the following advice:
Fend off overexposure. Sun protection is vital. Minimize exposure to direct sunlight and seek shade from 10 a.m. to 4 p.m., when UV radiation is most intense, but remember that shade structures may not offer complete protection. 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.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the temperatures in September?
What is the average humidity in September?
How much does it rain in September?
What is the average length of the day in September?
When are sunrise and sunset in September?
How long on average sun shines in September?
What are the months with the highest UV index?
How high is the UV index in September?
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).
Average pressure in September
Westmont, CA
- Average pressure in September: 29.9"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).
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).
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%).
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").
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).
Average daylight in September /
Average sunshine in September
Westmont, CA
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 9h and 54min).
- Average sunshine in September: 10h and 3min
The months with the most sunshine are July and August (Average sunshine: 11h and 54min).
The month with the least sunshine is December (Average sunshine: 6h and 42min).
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).
Average UV index in September
Westmont, CA
- Average UV index in September: 6
The months with the highest UV index are June, July, August and September (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 4).
Average cloud cover in September
Westmont, CA
- Average cloud cover in September: 11
The 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).
Average visibility in September
Westmont, 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).
Westmont, California, USA
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