September weather forecast
Niwot, CO

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Weather in September

September, the first month of the autumn in Niwot, is also a moderately hot month, with temperature in the range of an average high of 77.2°F (25.1°C) and an average low of 51.1°F (10.6°C).

Temperature

Niwot's transition into September involves a gentle shift in temperature, receding from a moderately hot 84.7°F (29.3°C) in August to a still warm 77.2°F (25.1°C). Despite the stark contrast with daytime temperatures, Niwot's September nights average at a cool 51.1°F (10.6°C).

Humidity

In Niwot, the average relative humidity in September is 43%.

Rainfall

In Niwot, in September, during 9.7 rainfall days, 0.75" (19mm) of precipitation is typically accumulated. In Niwot, during the entire year, the rain falls for 105.4 days and collects up to 10.43" (265mm) of precipitation.

Snowfall

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

Daylight

The average length of the day in September is 12h and 26min.
On the first day of the month, sunrise is at 6:29 am and sunset at 7:31 pm. On the last day of September, sunrise is at 6:56 am and sunset at 6:44 pm MDT.

Sunshine

In Niwot, the average sunshine in September is 11h.

UV index

In September, the average daily maximum UV index is 4. A UV Index value of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV rays for the average person.
Note: In September, an average UV index of 4 transforms into the following instructions:
Prioritize safety - The need to safeguard skin and eyes from harm is emphasized. Limiting exposure to the direct Sun during midday hours can help prevent harmful UV radiation effects. Shield yourself from the harmful effects of UV radiation with sun-protective attire, a hat, and quality sunglasses. Take into account! The reflection from snow can nearly double the Sun's UV radiation intensity.
Updated: Feb 10, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the usual temperature for Niwot in September?

In September, the average high-temperature and low-temperature in Niwot are 77.2°F (25.1°C) and 51.1°F (10.6°C) respectively. In August, the average heat index (a.k.a. 'feels like', 'apparent temperature'), which takes the relative humidity and factors it into the air temperature reading, is estimated at 84.2°F (29°C).

What is the average humidity in September in Niwot?

In September, the average relative humidity in Niwot is 43%.

How much does it rain in Niwot in September?

In Niwot, during September, the rain falls for 9.7 days and regularly aggregates up to 0.75" (19mm) of precipitation.

When it does not snow in Niwot?

June through September are months without snowfall.

Does it snow in Niwot in September?

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

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

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

What time are sunrise and sunset in September in Niwot?

On the first day of September in Niwot, sunrise is at 6:29 am and sunset at 7:31 pm. On the last day of the month, sunrise is at 6:56 am and sunset at 6:44 pm MDT.

How many hours of sunshine does Niwot have in September?

In Niwot, the average sunshine duration in September is 11h.

What is the UV index intensity in September in Niwot?

In September, the average daily maximum UV index is 4. A UV Index value of 3 to 5 symbolizes a moderate vulnerability from exposure to Sun's UV rays.
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
Niwot, CO

Average temperature in September - Niwot, CO
  • Average high temperature in September: 77.2°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 (39°F).

  • Average low temperature in September: 51.1°F

The month with the highest average low temperature is July (59.2°F).
The coldest month (with the lowest average low temperature) is December (19.9°F).

Average pressure in September
Niwot, CO

Average pressure in September - Niwot, CO
  • Average pressure in September: 30"Hg

The month with the highest atmospheric pressure is January (30.15"Hg).
The months with the lowest atmospheric pressure are April and June (29.91"Hg).

Average wind speed in September
Niwot, CO

Average wind speed in September - Niwot, CO
  • Average wind speed in September: 5.6mph

The windiest months (with the highest average wind speed) are March and April (6.6mph).
The calmest months (with the lowest average wind speed) are August and September (5.6mph).

Average humidity in September
Niwot, CO

Average humidity in September - Niwot, CO
  • Average humidity in September: 43%

The month with the highest relative humidity is February (66%).
The month with the lowest relative humidity is August (42%).

Average rainfall in September
Niwot, CO

Average rainfall in September - Niwot, CO
  • Average rainfall in September: 0.75"

The wettest month (with the highest rainfall) is May (1.69").
The driest month (with the least rainfall) is January (0.35").

Average rainfall days in September
Niwot, CO

Average rainfall days in September - Niwot, CO
  • Average rainfall days in September: 9.7 days

The month with the highest number of rainy days is July (16 days).
The month with the least rainy days is January (3.5 days).

Average snowfall in September
Niwot, CO

Average snowfall in September - Niwot, CO
  • Average snowfall in September: 0"

The month with the highest snowfall is November (4.41").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in September
Niwot, CO

Average snowfall days in September - Niwot, CO
  • Average snowfall days in September: 0.1 days

The month with the highest number of snowfall days is February (7.7 days).
The months with the least snowfall days are June, July and August (0 days).

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

Average daylight in September / Average sunshine in September - Niwot, 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 0min

The month with the most sunshine is June (Average sunshine: 11h and 54min).
The month with the least sunshine is February (Average sunshine: 6h and 48min).

Average sunshine days in September
Niwot, CO

Average sunshine days in September - Niwot, CO
  • Average sunshine days in September: 16.5 days

The month with the most sunshine days is January (23.4 days).
The month with the least sunshine days is July (9.3 days).

Average UV index in September
Niwot, CO

Average UV index in September - Niwot, CO
  • Average UV index in September: 4

The months with the highest UV index are 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
Niwot, CO

Average cloud cover in September - Niwot, CO
  • Average cloud cover in September: 16

The months with the most cloud cover are April and May (Cloud cover 26).
The months with the least cloud cover are June and September (Cloud cover 16).

Average visibility in September
Niwot, CO

Average visibility in September - Niwot, 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).

Niwot, Colorado, USA

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