September weather forecastJefferson, CO
September
Weather in September
The first month of the autumn, September, is still a mild month in Jefferson, Colorado, with an average temperature varying between 57.6°F (14.2°C) and 33.4°F (0.8°C).Temperature
The arrival of September corresponds with a minor reduction in the average high-temperature, down from August's refreshing 63.7°F (17.6°C) to a moderate 57.6°F (14.2°C). Jefferson records a consistent low-temperature average of 33.4°F (0.8°C) during September, indicating a significant difference from the daytime heat.Humidity
The average relative humidity in September is 59%.Rainfall
In Jefferson, during September, the rain falls for 11.5 days and regularly aggregates up to 1.46" (37mm) of precipitation. In Jefferson, during the entire year, the rain falls for 110.4 days and collects up to 24.09" (612mm) of precipitation.Snowfall
Months with snowfall in Jefferson are January through December. In Jefferson, in September, during 5.5 snowfall days, 2.05" (52mm) of snow is typically accumulated. In Jefferson, Colorado, during the entire year, snow falls for 158 days and aggregates up to 118.82" (3018mm) of snow.Daylight
In Jefferson, Colorado, the average length of the day in September is 12h and 26min.On the first day of September, sunrise is at 6:32 am and sunset at 7:33 pm. On the last day of the month, sunrise is at 6:59 am and sunset at 6:46 pm MDT.
Sunshine
The average sunshine in September is 10.5h.UV index
In September, the average daily maximum UV index is 2. A UV Index of 2, and less, symbolizes a minimal health hazard from unsafe exposure to UV radiation for the average person.Note: In September, a regular UV index of 2 translates into these guidelines:
The majority are not significantly affected by prolonged sun exposure. Infants, children, and those with fair skin must always have protection. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Employ a wide-brim hat for potent defense against up to 50% of UV rays. Note this! The Sun's UV radiation can nearly be doubled by the reflection off snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Jefferson, CO
- Average high temperature in September: 57.6°F
The warmest month (with the highest average high temperature) is July (65.8°F).
The month with the lowest average high temperature is December (21.2°F).
- Average low temperature in September: 33.4°F
The month with the highest average low temperature is July (40.1°F).
The coldest months (with the lowest average low temperature) are January and December (0.7°F).
Average pressure in September
Jefferson, CO
- Average pressure in September: 30.05"Hg
The month with the highest atmospheric pressure is January (30.19"Hg).
The months with the lowest atmospheric pressure are April and May (29.94"Hg).
Average wind speed in September
Jefferson, CO
- Average wind speed in September: 5.2mph
The windiest month (with the highest average wind speed) is February (7mph).
The calmest month (with the lowest average wind speed) is August (4.8mph).
Average humidity in September
Jefferson, CO
- Average humidity in September: 59%
The month with the highest relative humidity is February (89%).
The month with the lowest relative humidity is June (54%).
Average rainfall in September
Jefferson, CO
- Average rainfall in September: 1.46"
The wettest month (with the highest rainfall) is July (3.35").
The driest month (with the least rainfall) is November (1.14").
Average rainfall days in September
Jefferson, CO
- Average rainfall days in September: 11.5 days
The month with the highest number of rainy days is July (22.8 days).
The month with the least rainy days is November (2.8 days).
Average snowfall in September
Jefferson, CO
- Average snowfall in September: 2.05"
The month with the highest snowfall is May (19.69").
The month with the least snowfall is July (0.24").
Average snowfall days in September
Jefferson, CO
- Average snowfall days in September: 5.5 days
The month with the highest number of snowfall days is April (22.8 days).
The month with the least snowfall days is July (1.3 days).
Average daylight in September /
Average sunshine in September
Jefferson, CO
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in September: 10h and 30min
The month with the most sunshine is June (Average sunshine: 11h and 24min).
The month with the least sunshine is February (Average sunshine: 5h and 12min).
Average sunshine days in September
Jefferson, CO
- Average sunshine days in September: 14.1 days
The month with the most sunshine days is November (18.5 days).
The month with the least sunshine days is July (5.8 days).
Average UV index in September
Jefferson, CO
- Average UV index in September: 2
The months with the highest UV index are May, June, July and August (UV index 3).
The months with the lowest UV index are February and December (UV index 1).
Average cloud cover in September
Jefferson, CO
- Average cloud cover in September: 22
The month with the most cloud cover is February (Cloud cover 54).
The month with the least cloud cover is June (Cloud cover 19).
Average visibility in September
Jefferson, CO
- Average visibility in September: 6mi
The months with the highest visibility are June, July, August, September and October (6mi).
The months with the lowest visibility are January, February, March, April and December (4mi).
