September weather forecastDanville, CA
September
Weather in September
September, the first month of the autumn in Danville, is still a warm month, with an average temperature varying between 56.7°F (13.7°C) and 82°F (27.8°C).Temperature
The advent of September signifies a minor shift to an average high-temperature of a still warm 82°F (27.8°C), aligning closely with August. Danville, amid September nights, sees a noteworthy disparity from daily highs with an average temperature of 56.7°F (13.7°C).Heat index
The heat index in September is computed to be 84.2°F (29°C). Continuing activity during long-lasting exposure might induce tiredness and result in heat cramps.One should consider that heat index numbers are for shaded settings and light wind. The heat index values could be amplified by up to 15 Fahrenheit (8 Celsius) degrees in direct sunlight.
Note: The heat index, also known as 'real feel' or 'felt air temperature', is a calculation that merges air temperature and relative humidity to depict the sensation of warmth. The individual's temperature perception can be influenced by numerous factors such as metabolic variations, physical activity, and clothing. Keep aware, the sun, when shining directly, can intensify the heat experience, pushing the heat index up by 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially vital to children. Typically, children face more danger than adults as they usually perspire less. Their larger skin surface relative to their small bodies and increased heat output from their activities enhance their risk.
Humidity
September is the least humid month in Danville, with an average relative humidity of 57%.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. In Danville, during the entire year, the rain falls for 65.6 days and collects up to 11.22" (285mm) of precipitation.Daylight
In September, the average length of the day in Danville is 12h and 25min.On the first day of September, sunrise is at 6:38 am and sunset at 7:36 pm. On the last day of the month, sunrise is at 7:03 am and sunset at 6:51 pm PDT.
Sunshine
In Danville, the average sunshine in September is 11.1h.UV index
In Danville, the average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to UV radiation for the average person.Note: A daily high UV index of 5 in September leads to these guidelines:
Stay alert. Light-skinned people could suffer burns in less than 30 minutes. Limiting exposure to the direct Sun during midday hours can help prevent harmful UV radiation effects. A hat with a broad brim is indispensable, filtering out up to half of UV rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Danville, 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
Danville, 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
Danville, 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
Danville, 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
Danville, 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
Danville, 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
Danville, CA
- Average daylight in September: 12h and 24min
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 6min
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
Danville, 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
Danville, 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
Danville, 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
Danville, 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).
