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
In September, the average high-temperature is practically the same as in August - a still moderately hot 82°F (27.8°C). In September, the average low-temperature is 56.7°F (13.7°C).Heat index
The average heat index in September is evaluated at 84.2°F (29°C). Constant exposure and activity lead to possible fatigue. Prolonged exercise may result in heat cramps.Take into consideration that the heat index values are calculated for shade and light wind conditions. 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 'apparent temperature', 'feels like', 'felt air temperature', or 'real feel', is what the temperature feels like to the human body when the air temperature is combined with the relative humidity. Additional factors like pregnancy, differences in body mass, height, and shape, wind, and activity influence one's weather impression. 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 particularly important for children. 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
With an average relative humidity of 57%, September is the least humid month.Rainfall
January through June, September through December are months with rainfall. September is the first month it rains. Throughout September, in the average 1.7 rainfall days, it receives 0.08" (2mm) of precipitation. Throughout the year, in Diablo, California, there are 65.6 rainfall days, and 11.22" (285mm) of precipitation is accumulated.Daylight
In September, the average length of the day is 12h and 25min.On the first day of September in Diablo, sunrise is at 6:37 am and sunset at 7:37 pm. On the last day of the month, sunrise is at 7:02 am and sunset at 6:52 pm PDT.
Sunshine
In September, the average sunshine is 11.1h.UV index
In September, the average daily maximum UV index is 5. A UV Index reading of 3 to 5 represents a moderate threat to health from unprotected exposure to Sun's UV rays for the average person.Note: The daily maximum UV index of 5 in September interpret into the following advice:
Take precautions - Protection against sun damage is advised. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
FAQ
What is the temperature in September in Diablo?
What is the least humid month in Diablo?
What is the average humidity in September in Diablo?
When does it start raining in Diablo?
How many hours of daylight does Diablo have in September?
When are sunrise and sunset in September in Diablo?
How long on average sun shines in September in Diablo?
What is the UV index intensity in September in Diablo?
Average temperature in September
Diablo, CA
- Average high temperature in September: 82°F
The warmest month (with the highest average high temperature) is July (83.8°F).
The month with the lowest average high temperature is December (55.8°F).
- Average low temperature in September: 56.7°F
The months with the highest average low temperature are August and September (56.7°F).
The coldest month (with the lowest average low temperature) is January (42.1°F).
Average pressure in September
Diablo, CA
- Average pressure in September: 29.92"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.92"Hg).
Average wind speed in September
Diablo, CA
- Average wind speed in September: 5.4mph
The windiest month (with the highest average wind speed) is May (6.9mph).
The calmest month (with the lowest average wind speed) is November (4.3mph).
Average humidity in September
Diablo, CA
- Average humidity in September: 57%
The month with the highest relative humidity is March (74%).
The month with the lowest relative humidity is September (57%).
Average rainfall in September
Diablo, CA
- Average rainfall in September: 0.08"
The wettest month (with the highest rainfall) is February (2.36").
The driest months (with the least rainfall) are July and August (0").
Average rainfall days in September
Diablo, CA
- Average rainfall days in September: 1.7 days
The month with the highest number of rainy days is March (12.6 days).
The month with the least rainy days is August (0.6 days).
Average daylight in September /
Average sunshine in September
Diablo, CA
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in September: 11h and 1min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 5h and 48min).
Average sunshine days in September
Diablo, CA
- Average sunshine days in September: 27.2 days
The month with the most sunshine days is July (30.2 days).
The month with the least sunshine days is March (17.6 days).
Average UV index in September
Diablo, 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).
Average cloud cover in September
Diablo, CA
- Average cloud cover in September: 10
The month with the most cloud cover is March (Cloud cover 36).
The month with the least cloud cover is July (Cloud cover 6).
Average visibility in September
Diablo, 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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