September weather forecastThornton, CO
September
Weather in September
The first month of the autumn, September, is still a warm month in Thornton, Colorado, with an average temperature ranging between max 79.5°F (26.4°C) and min 53.8°F (12.1°C).Temperature
September's arrival comes with a mild decrease in the average high-temperature, moving subtly from a tropical 87.1°F (30.6°C) in August to a moderately hot 79.5°F (26.4°C). Thornton measures a considerable dip from daytime highs with an average low-temperature of 53.8°F (12.1°C) during September.Humidity
The average relative humidity in September is 41%.Rainfall
In September, the rain falls for 3.3 days. Throughout September, 0.16" (4mm) of precipitation is accumulated. In Thornton, during the entire year, the rain falls for 48.3 days and collects up to 3.19" (81mm) of precipitation.Snowfall
June through September are months without snowfall.Daylight
The average length of the day in September is 12h and 26min.On the first day of September, sunrise is at 6:28 am and sunset at 7:30 pm. On the last day of the month, sunrise is at 6:55 am and sunset at 6:43 pm MDT.
Sunshine
In September, the average sunshine is 11.1h.UV index
In September, the average daily maximum UV index in Thornton is 5. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for the average person.Note: The maximum daily UV index, 5 in September, converts into the following recommendations:
Prioritize safety - The need to safeguard skin and eyes from harm is emphasized. The best time to avoid the Sun's harmful UV radiation is during midday when it's most potent. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Thornton, CO
- Average high temperature in September: 79.5°F
The warmest month (with the highest average high temperature) is July (88.3°F).
The month with the lowest average high temperature is December (41.2°F).
- Average low temperature in September: 53.8°F
The month with the highest average low temperature is July (61.7°F).
The coldest month (with the lowest average low temperature) is December (21.9°F).
Average pressure in September
Thornton, CO
- Average pressure in September: 30"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are April and June (29.91"Hg).
Average wind speed in September
Thornton, CO
- Average wind speed in September: 5.9mph
The windiest month (with the highest average wind speed) is April (6.9mph).
The calmest month (with the lowest average wind speed) is December (5.8mph).
Average humidity in September
Thornton, CO
- Average humidity in September: 41%
The month with the highest relative humidity is February (64%).
The month with the lowest relative humidity is August (39%).
Average rainfall in September
Thornton, CO
- Average rainfall in September: 0.16"
The wettest month (with the highest rainfall) is July (0.59").
The driest months (with the least rainfall) are January and December (0.08").
Average rainfall days in September
Thornton, CO
- Average rainfall days in September: 3.3 days
The month with the highest number of rainy days is July (8.2 days).
The month with the least rainy days is February (1.2 days).
Average snowfall in September
Thornton, CO
- Average snowfall in September: 0"
The month with the highest snowfall is October (1.42").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Thornton, CO
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (4.7 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Thornton, CO
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in September: 11h and 6min
The months with the most sunshine are June and July (Average sunshine: 11h and 54min).
The month with the least sunshine is February (Average sunshine: 6h and 42min).
Average sunshine days in September
Thornton, CO
- Average sunshine days in September: 24.5 days
The month with the most sunshine days is December (28.5 days).
The month with the least sunshine days is July (19.6 days).
Average UV index in September
Thornton, CO
- 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 2).
Average cloud cover in September
Thornton, CO
- Average cloud cover in September: 14
The months with the most cloud cover are February, April and May (Cloud cover 25).
The month with the least cloud cover is September (Cloud cover 14).
Average visibility in September
Thornton, CO
- 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).
