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 snowfall in September
- Average snowfall 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
With the transition into September, Mount Wilson notes an average high-temperature of a warm 83.8°F (28.8°C), closely resembling August. During September nights, Mount Wilson documents a marked contrast from daily highs, with an average temperature of 61.9°F (16.6°C).Heat index
The heat index for September is computed to be 84.2°F (29°C). Long-standing exposure coupled with ongoing activity could result in exhaustion, possibly causing heat cramps.Heat index readings emphasize conditions of light breezes and shaded spots. In the presence of direct sunshine, the heat index could be augmented by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'felt air temperature', offers an insight into how hot it feels when we factor in moisture content. The impact of weather is personal, differing among a variety of people based on differences in body mass, height, and the level of physical exertion. It is noteworthy that being in direct sunlight can enhance the weather's impact, raising the heat index by as much as 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Kids often lack the knowledge about the necessity to take breaks and consume liquids. Thirst, as a late symptom of dehydration, necessitates the maintenance of hydration, particularly during enduring physical activities.
Humidity
The average relative humidity in September in Mount Wilson is 47%.Rainfall
In Mount Wilson, in September, it is raining for 3.4 days, with typically 0.2" (5mm) of accumulated precipitation. In Mount Wilson, during the entire year, the rain falls for 50.3 days and collects up to 8.7" (221mm) of precipitation.Snowfall
In Mount Wilson, snow does not fall in May through October.Daylight
The average length of the day in September is 12h and 22min.On the first day of the month, sunrise is at 6:26 am and sunset at 7:17 pm. On the last day of September, in Mount Wilson, sunrise is at 6:46 am and sunset at 6:37 pm PDT.
Sunshine
In Mount Wilson, the average sunshine in September is 10.8h.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 vulnerability from exposure to the Sun's UV radiation for average individuals.Note: A maximum high daily UV index of 6 during September translates into the following directions:
Evade overexposure. Individuals with fair skin risk burning in under 20 minutes. UV radiation from the sun is at its strongest between 10 a.m. and 4 p.m. Try to limit direct exposure during these hours. Experience reduced UV exposure by about half when donning a wide-brim hat.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How hot is it in September?
What is the average humidity in September?
How much does it rain in September?
When it does not snow?
What is the average length of the day in September?
When is the sunrise / sunset in September?
How long on average sun shines in September?
When is the highest UV index?
What is the UV index intensity in September?
Average temperature in September
Mount Wilson, CA
- Average high temperature in September: 83.8°F
The warmest month (with the highest average high temperature) is August (86.2°F).
The month with the lowest average high temperature is December (58.5°F).
- Average low temperature in September: 61.9°F
The month with the highest average low temperature is August (64°F).
The coldest month (with the lowest average low temperature) is December (43.3°F).
Average pressure in September
Mount Wilson, CA
- Average pressure in September: 29.89"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed in September
Mount Wilson, CA
- Average wind speed in September: 4.5mph
The windiest month (with the highest average wind speed) is April (6mph).
The calmest month (with the lowest average wind speed) is September (4.5mph).
Average humidity in September
Mount Wilson, CA
- Average humidity in September: 47%
The month with the highest relative humidity is March (56%).
The month with the lowest relative humidity is August (45%).
Average rainfall in September
Mount Wilson, CA
- Average rainfall in September: 0.2"
The wettest month (with the highest rainfall) is February (1.73").
The driest month (with the least rainfall) is June (0.08").
Average rainfall days in September
Mount Wilson, CA
- Average rainfall days in September: 3.4 days
The month with the highest number of rainy days is March (6.4 days).
The month with the least rainy days is June (1.3 days).
Average snowfall in September
Mount Wilson, CA
- Average snowfall in September: 0"
The month with the highest snowfall is December (2.99").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Mount Wilson, CA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (1.3 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Mount Wilson, 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 5min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The months with the least sunshine are January, February and December (Average sunshine: 6h and 54min).
Average sunshine days in September
Mount Wilson, CA
- Average sunshine days in September: 25.6 days
The month with the most sunshine days is June (27.9 days).
The month with the least sunshine days is February (21.4 days).
Average UV index in September
Mount Wilson, 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 November and December (UV index 3).
Average cloud cover in September
Mount Wilson, CA
- Average cloud cover in September: 7
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 5).
Average visibility in September
Mount Wilson, 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).
Mount Wilson, California, USA
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