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 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
Start of September brings a slight shift in the average high-temperature, dipping a bit from August's warm 84.7°F (29.3°C) to a still moderately hot 77.2°F (25.1°C). Niwot records a marked divergence from the day's high temperatures, with nights in September averaging at a fresh 51.1°F (10.6°C).Humidity
The average relative humidity in September is 43%.Rainfall
In September, the rain falls for 9.7 days. Throughout September, 0.75" (19mm) of precipitation is accumulated. In Niwot, during the entire year, the rain falls for 105.4 days and collects up to 10.43" (265mm) of precipitation.Snowfall
June through September are months without snowfall.Daylight
In Niwot, Colorado, 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 September, the average sunshine is 11h.UV index
In September, the average daily maximum UV index is 4. A UV Index estimate of 3 to 5 represents a medium health hazard from unsafe exposure to UV radiation for average individuals.Note: The daily maximum UV index of 4 in September interprets into the following advice:
Adopt protective measures - Suggestions to resist sunburn are offered. Avoid the Sun's strongest UV rays by seeking shade and limiting exposure during midday. For a sun-safe wardrobe, go for clothes that are tightly woven and generously sized. Be careful! The Sun's UV radiation can nearly be doubled by the reflective quality of snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Niwot in September?
What is the average humidity in September?
How many days does it rain in September?
When it does not snow?
Does it snow in September?
How many hours of daylight does Niwot 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
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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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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