Air quality index56Moderate

Acceptable for most people; unusually sensitive people should take it easier outdoors.

Next 24 hours

US AQI

59Now
57
55
533 AM
51
52
526 AM
53
54
549 AM
55
58
6012 PM
63
65
683 PM
71
72
736 PM
75
69
649 PM
59
59

Air quality outlook

Worst hour each day

Today75Moderate
Fri 963Moderate
Sat 1049Good
Sun 1144Good
Mon 1241Good

From our air-quality forecast models (GEOS-CF / GEFS aerosols). AQI uses the US EPA scale.

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About Boulder weather

Boulder is in Boulder County, Colorado, United States at 40.01°, -105.27°. Right now it’s 66° and clear; today’s high is 84° with a 3% chance of rain.

Colorado's climate is defined by dramatic elevation changes, from the eastern plains at around 3,500 feet to over 50 peaks exceeding 14,000 feet in the Rocky Mountains. Denver, known as the Mile High City, enjoys over 300 days of sunshine per year and has a semi-arid climate with low humidity. Temperature swings of 40 degrees or more in a single day are not uncommon along the Front Range.