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
With the transition into September, Yountville notes an average high-temperature of a moderately hot 84°F (28.9°C), closely resembling August. Yountville receives a consistent average low-temperature of 55.2°F (12.9°C) in September, a substantial dip from the day's heat.Heat index
In September, the average heat index is evaluated at a tropical 86°F (30°C). If one continues to be active during exposure, it might cause tiredness and subsequent heat cramps.When considering the heat index, it's pivotal to note it is for shade and mild wind conditions. Heat index values may rise by up to 15 Fahrenheit (8 Celsius) degrees when exposed to direct sunlight.
Note: The heat index, also known as 'real feel' or 'apparent temperature', takes into account both air temperature and humidity to illustrate what people actually feel. The impression of weather on a person can be swayed by additional aspects, including metabolic variations, pregnancy, and activity levels. By being directly under the sun, it's possible for the felt temperature to increase by 15 Fahrenheit (8 Celsius) degrees. Heat index values are extremely significant for children. Children often overlook the need for breaks and fluid intake. Thirst is a late-stage sign of dehydration - hence, it is necessary to stay hydrated, especially during extended periods of physical activities.
Humidity
The least humid month in Yountville, California, is September, with an average relative humidity of 54%.Rainfall
In Yountville, in September, during 2.1 rainfall days, 0.08" (2mm) of precipitation is typically accumulated. In Yountville, during the entire year, the rain falls for 77.8 days and collects up to 16.02" (407mm) of precipitation.Daylight
The average length of the day in September is 12h and 25min.On the first day of the month, sunrise is at 6:39 am and sunset at 7:38 pm. On the last day of September, in Yountville, sunrise is at 7:05 am and sunset at 6:53 pm PDT.
Sunshine
In Yountville, the average sunshine in September is 11.1h.UV index
The average daily maximum UV index in September is 5. A UV Index estimate of 3 to 5 represents a medium health hazard from exposure to the Sun's UV radiation for ordinary individuals.Note: The daily high UV index of 5 during September translates into the following recommendations:
Be vigilant - Preventing sunburn is recommended. Protect yourself from the midday Sun's peak UV radiation by minimizing exposure. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes.
Frequently asked questions
How hot is September in Yountville?
What is the least humid month in Yountville?
What is the average humidity in September in Yountville?
How many days does it rain in September in Yountville?
How many hours of daylight does Yountville have in September?
When are sunrise and sunset in September in Yountville?
How long on average sun shines in September in Yountville?
How high is the UV index in September in Yountville?
Average temperature in September
Yountville, CA
- Average high temperature in September: 84°F
The warmest month (with the highest average high temperature) is July (86.5°F).
The month with the lowest average high temperature is December (54.5°F).
- Average low temperature in September: 55.2°F
The month with the highest average low temperature is August (55.4°F).
The coldest month (with the lowest average low temperature) is December (40.1°F).
Average pressure in September
Yountville, 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 and August (29.91"Hg).
Average wind speed in September
Yountville, CA
- Average wind speed in September: 4.7mph
The windiest month (with the highest average wind speed) is May (6mph).
The calmest month (with the lowest average wind speed) is November (4.3mph).
Average humidity in September
Yountville, CA
- Average humidity in September: 54%
The month with the highest relative humidity is March (76%).
The month with the lowest relative humidity is September (54%).
Average rainfall in September
Yountville, CA
- Average rainfall in September: 0.08"
The wettest month (with the highest rainfall) is February (3.43").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in September
Yountville, CA
- Average rainfall days in September: 2.1 days
The month with the highest number of rainy days is March (13.9 days).
The month with the least rainy days is August (0.9 days).
Average daylight in September /
Average sunshine in September
Yountville, CA
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in September: 11h and 1min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 36min).
Average sunshine days in September
Yountville, CA
- Average sunshine days in September: 26.9 days
The month with the most sunshine days is July (29.4 days).
The month with the least sunshine days is March (15.8 days).
Average UV index in September
Yountville, 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
Yountville, CA
- Average cloud cover in September: 9
The month with the most cloud cover is March (Cloud cover 40).
The month with the least cloud cover is July (Cloud cover 6).
Average visibility in September
Yountville, 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).
Yountville, California, USA
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