September weather forecast
Thornton, CO

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Weather in September

September, the first month of the autumn in Thornton, is still a warm month, with an average temperature fluctuating between 53.8°F (12.1°C) and 79.5°F (26.4°C).

Temperature

The onset of September aligns with a soft reduction in the average high-temperature, gently falling from a hot 87.1°F (30.6°C) in August to a moderately hot 79.5°F (26.4°C). Throughout September, Thornton registers a distinct decrease from daytime highs, reaching an average low of 53.8°F (12.1°C).

Humidity

The average relative humidity in September in Thornton is 41%.

Rainfall

In Thornton, in September, during 3.3 rainfall days, 0.16" (4mm) of precipitation is typically accumulated. In Thornton, during the entire year, the rain falls for 48.3 days and collects up to 3.19" (81mm) of precipitation.

Snowfall

In Thornton, snow does not fall in June through September.

Daylight

In Thornton, Colorado, 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 is 5. A UV Index reading of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV radiation for ordinary individuals.
Note: In September, the maximum UV index of 5 translates into these guidelines:
Take necessary precautions - Defending against sun damage is advocated. To protect against the Sun's most potent rays, avoid direct exposure around midday. Sun protection is enhanced with clothing that boasts a tight weave yet offers a loose fit.
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Frequently asked questions

What is the temperature in September in Thornton?

The average high-temperature and low-temperature in Thornton, Colorado, during September are 79.5°F (26.4°C) and 53.8°F (12.1°C) respectively. The average heat index (a.k.a. 'apparent temperature', 'real feel'), which represents the influence of relative humidity on air temperature, in July is appraised at 89.6°F (32°C).

What is the average humidity in September in Thornton?

The average relative humidity in September in Thornton, Colorado, is 41%.

How much does it rain in Thornton in September?

In Thornton, in September, it is raining for 3.3 days, with typically 0.16" (4mm) of accumulated precipitation.

When it does not snow in Thornton?

June through September are months without snowfall in Thornton.

Does it snow in Thornton in September?

In Thornton, Colorado, in September, it doesn't snow. In October, it regularly snows.

What is the average length of the day in September in Thornton?

In September, the average day length in Thornton, Colorado, is 12h and 26min.

What time are sunrise and sunset in September in Thornton?

In September, on the first day of the month, sunrise is at 6:28 am and sunset at 7:30 pm. On the last day of the month, in Thornton, Colorado, sunrise is at 6:55 am and sunset at 6:43 pm MDT.

How many hours of sunshine does Thornton have in September?

In Thornton, the average sunshine duration in September is 11.1h.

How high is the UV index in September in Thornton?

In Thornton, Colorado, the average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a moderate health threat from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Thornton, CO

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).

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Average pressure in September
Thornton, CO

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).

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Average wind speed in September
Thornton, CO

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).

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Average humidity in September
Thornton, CO

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%).

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Average rainfall in September
Thornton, CO

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").

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Average rainfall days in September
Thornton, CO

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).

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Average snowfall in September
Thornton, CO

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").

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Average snowfall days in September
Thornton, CO

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).

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Average daylight in September /
Average sunshine in September
Thornton, CO

Average daylight in September / Average sunshine in September - Thornton, CO
  • Average daylight in September: 12h and 2min

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 1min

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).

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Average sunshine days in September
Thornton, CO

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).

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Average UV index in September
Thornton, CO

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).

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Average cloud cover in September
Thornton, CO

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).

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Average visibility in September
Thornton, CO

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).

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Thornton, Colorado, USA

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