Weather in Boulder: September
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Average day temperature: | 70.4°F |
| Average night temperature: | 51.8°F | |
 |
Number of sunny days: | 18 days |
| Day length: | 11.8 - 13.1 hours | |
 |
Number of rainy days: | 1 day |
| Precipitation totals: | 0.7 in. | |
| more information | ||
14 days
forecast
forecast
| Boulder |
weather in
October
October
| Boulder |
Air temperature in September, °F
Show year:
2026
2025
2024
The highest day temperature during September of 2026 was 87°F. At the same time the lowest night temperature was 48°F. Daily and nightly averages during September were 75.9°F and 58.0°F.
Sunny, partly cloudy and cloudy days
Mostly all days in September are sunny but cloudy days are also possible.
Precipitation total in September, in.
Precipitation total value in Boulder in September is 0.7 in. Other months of the year show relatively similar values.
Wind speed in September, mph
The average wind speed value in September is 6.5 mph It makes September one of the least windy months of the year.
Average sunny hours
This chart shows average number of hours during the day when sunlight can reach the ground. It depends on day length and cloudiness during the day. The average number of sunny hours in September is: 8.5.
Best time for vacation in Boulder
Boulder on a weather map
Places in USA:
Name
°F
24 Hours Forecast
Boulder
Local time: 10:27
October 29, thursday
1200
59°F
W
4 mph
4 mph
1500
63°F
W
4 mph
4 mph
1800
48°F
S
2 mph
2 mph
2100
45°F
E
4 mph
4 mph
October 30, friday
0000
41°F
E
3 mph
3 mph
0300
39°F
E
2 mph
2 mph
0600
39°F
E
2 mph
2 mph
0900
46°F
NE
1 mph
1 mph
