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
The dawn of September sees an average high-temperature of a still moderately hot 83.5°F (28.6°C), subtly contrasting with August's 85.1°F (29.5°C). Clayton observes a distinct decrease from peak daytime temperatures, with an average low-temperature of 57.6°F (14.2°C) throughout the month of September.Heat index
The heat index for September is estimated at a hot 86°F (30°C). Continued exposure and engagement in activity might trigger tiredness and subsequently heat cramps.Bear in mind that the heat index values are determined for shaded areas and light breezes. The presence of direct sunlight can raise the heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'real feel', takes into account both air temperature and humidity to illustrate what people actually feel. This effect is personal, influenced by the individual's physical activity and heat sensitivity, shaped by factors including wind, attire, and metabolic variations. With direct sunlight, be aware that it might enhance the heat sensation, raising the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values remain especially vital for babies and toddlers. Children often fail to understand the importance of rest and rehydration. Thirst is a late manifestation of dehydration - hence, it is crucial to stay hydrated, especially during ongoing physical activities.
Humidity
September and October, with an average relative humidity of 55%, are the least humid months in Clayton.Rainfall
In Clayton, in September, during 1.8 rainfall days, 0.08" (2mm) of precipitation is typically accumulated. Throughout the year, there are 50 rainfall days, and 4.76" (121mm) of precipitation is accumulated.Daylight
The average length of the day in September 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 September, the average sunshine in Clayton is 11.2h.UV index
In September, the average daily maximum UV index in Clayton is 5. A UV Index estimate of 3 to 5 represents a moderate health risk from unsafe exposure to UV radiation for the average person.Note: A daily high UV index of 5 in September leads to these guidelines:
Adopt protective measures - Suggestions to resist sunburn are offered. Given the potency of the midday Sun's UV radiation, one should avoid prolonged exposure. For minimizing sun-related eye damage, always choose sunglasses with UVA and UVB coverage.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How hot does it get in Clayton in September?
What are the least humid months in Clayton?
What is the average humidity in September in Clayton?
How many days does it rain in September in Clayton?
What is the average length of the day in September in Clayton?
When is the sunrise / sunset in September in Clayton?
How many hours of sunshine does Clayton have in September?
What is the UV index reading in September in Clayton?
Average temperature in September
Clayton, CA
- Average high temperature in September: 83.5°F
The warmest month (with the highest average high temperature) is July (85.6°F).
The month with the lowest average high temperature is December (55.4°F).
- Average low temperature in September: 57.6°F
The month with the highest average low temperature is September (57.6°F).
The coldest month (with the lowest average low temperature) is January (41.7°F).
Average pressure in September
Clayton, CA
- Average pressure in September: 29.92"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in September
Clayton, CA
- Average wind speed in September: 5.8mph
The windiest month (with the highest average wind speed) is May (7.4mph).
The calmest month (with the lowest average wind speed) is November (4.3mph).
Average humidity in September
Clayton, CA
- Average humidity in September: 55%
The months with the highest relative humidity are January and March (73%).
The months with the lowest relative humidity are September and October (55%).
Average rainfall in September
Clayton, CA
- Average rainfall in September: 0.08"
The wettest month (with the highest rainfall) is February (0.98").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in September
Clayton, CA
- Average rainfall days in September: 1.8 days
The month with the highest number of rainy days is March (8.6 days).
The month with the least rainy days is August (0.8 days).
Average daylight in September /
Average sunshine in September
Clayton, 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 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
Clayton, CA
- Average sunshine days in September: 27.9 days
The month with the most sunshine days is August (29.4 days).
The month with the least sunshine days is March (21.7 days).
Average UV index in September
Clayton, 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
Clayton, CA
- Average cloud cover in September: 9
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
Clayton, 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).
Clayton, California, USA
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