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
The commencement of September includes a gentle temperature shift, with the average high-temperature dropping a bit from a tropical 87.1°F (30.6°C) in August to a warm 79.5°F (26.4°C). Marked by a significant temperature drop from daytime highs, the average nighttime temperature lowers to a cool 53.8°F (12.1°C) throughout September.Humidity
In September, the average relative humidity is 41%.Rainfall
In Derby, in September, it is raining for 3.3 days, with typically 0.16" (4mm) of accumulated precipitation. Throughout the year, there are 48.3 rainfall days, and 3.19" (81mm) of precipitation is accumulated.Snowfall
In Derby, snow does not fall in June through September.Daylight
In September, the average length of the day is 12h and 26min.On the first day of September in Derby, 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
The average sunshine in September is 11.1h.UV index
In Derby, the average daily maximum UV index in September is 5. A UV Index estimate of 3 to 5 represents a moderate health risk from exposure to the Sun's UV rays for the average person.Note: The maximum UV index of 5 during September leads to these instructions:
Undertake protective steps - Preventing sun damage is advised. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Sun-related eye harm can be minimized with proper sunglasses offering UVA and UVB coverage.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the temperatures 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 Derby have in September?
What time are sunrise and sunset in September?
How many hours of sunshine does Derby have in September?
How high is the UV index in September?
Average temperature in September
Derby, 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
Derby, 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
Derby, 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
Derby, 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
Derby, 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
Derby, 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
Derby, 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
Derby, 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
Derby, 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).
Average sunshine days in September
Derby, 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
Derby, 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
Derby, 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
Derby, 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).
Derby, Colorado, USA
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