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 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
Thornton records an average high-temperature of a still hot 88.5°F (31.4°C) in September, closely mirroring the climate of the previous month. In Thornton, a significant divergence from daytime highs is recorded, with average lows of 58.6°F (14.8°C) during September nights.Heat index
During September, the heat index is estimated at a hot 89.6°F (32°C). If activity and exposure persist, they could induce fatigue, leading to possible heat cramps.When assessing, remember that heat index measurements are for light winds and shaded spots. Direct sunlight can cause a surge in the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'felt air temperature', is the outcome of merging air's temperature and its humidity metrics. The impression of weather on a person can be swayed by additional aspects, including metabolic variations, pregnancy, and activity levels. In direct sunlight, the heat's impact can be heightened, potentially leading to an increase in the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are essentially critical for children. Young kids are often more at risk than adults as they tend to perspire less. Besides, their skin surface is larger relative to their small bodies, and their increased heat output from their active lifestyle compounds their risk.
Humidity
In Thornton, the average relative humidity in September is 46%.Rainfall
In September, the rain falls for 1.5 days. Throughout September, 0.08" (2mm) of precipitation is accumulated. In Thornton, during the entire year, the rain falls for 63.8 days and collects up to 12.6" (320mm) of precipitation.Snowfall
In Thornton, California, snow does not fall in January through November.Daylight
In Thornton, the average length of the day in September is 12h and 25min.On the first day of the month, sunrise is at 6:36 am and sunset at 7:34 pm. On the last day of September, sunrise is at 7:01 am and sunset at 6:49 pm PDT.
Sunshine
The average sunshine in September in Thornton is 11.3h.UV index
In September, the average daily maximum UV index is 5. A UV Index of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for the average person.Note: A daily high UV index of 5 in September leads to these guidelines:
Act with care - Obligation to protect against skin and eye damage is highlighted. Sun exposure should be minimized, especially during midday, to avoid harmful UV radiation. For optimum UV protection, wear sun-resistant attire complemented with a hat and quality shades.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How hot does it get in September?
What is the average humidity in September?
How many days does it rain in September?
When it does not snow?
How many hours of daylight does Thornton have in September?
What time are sunrise and sunset in September?
How long on average sun shines in September?
What is the UV index reading in September?
Average temperature in September
Thornton, CA
- Average high temperature in September: 88.5°F
The warmest month (with the highest average high temperature) is July (93.9°F).
The month with the lowest average high temperature is December (55°F).
- Average low temperature in September: 58.6°F
The month with the highest average low temperature is August (58.8°F).
The coldest month (with the lowest average low temperature) is December (41°F).
Average pressure in September
Thornton, CA
- Average pressure in September: 29.92"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in September
Thornton, CA
- Average wind speed in September: 4.6mph
The windiest months (with the highest average wind speed) are February and June (5.8mph).
The calmest month (with the lowest average wind speed) is November (4.4mph).
Average humidity in September
Thornton, CA
- Average humidity in September: 46%
The month with the highest relative humidity is March (75%).
The month with the lowest relative humidity is July (45%).
Average rainfall in September
Thornton, CA
- Average rainfall in September: 0.08"
The wettest month (with the highest rainfall) is February (2.4").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in September
Thornton, CA
- Average rainfall days in September: 1.5 days
The month with the highest number of rainy days is March (12.4 days).
The month with the least rainy days is June (0.9 days).
Average snowfall days in September
Thornton, CA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is December (0.1 days).
The months with the least snowfall days are January, February, March, April, May, June, July, August, September, October and November (0 days).
Average daylight in September /
Average sunshine in September
Thornton, 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 2min
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 54min).
Average sunshine days in September
Thornton, CA
- Average sunshine days in September: 27.5 days
The month with the most sunshine days is August (29.3 days).
The month with the least sunshine days is March (17.8 days).
Average UV index in September
Thornton, CA
- Average UV index in September: 5
The month with the highest UV index is June (UV index 7).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in September
Thornton, CA
- Average cloud cover in September: 7
The month with the most cloud cover is March (Cloud cover 35).
The month with the least cloud cover is July (Cloud cover 4).
Average visibility in September
Thornton, 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).
Thornton, California, USA
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