Boulder in September
Great time to visit
September delivers Boulder's most reliable weather with warm days, cool nights, and minimal storms. College students return, energizing the city without peak summer crowds.
Weather
September brings Boulder's second perfect season with warm days cooling to crisp nights. Afternoon storms fade to occasional showers. The dry air returns with crystal-clear mountain visibility.
26°C high10°C low6 rain days
Crowds & Cost
high crowds
~$170/day average
Events & Festivals
- •CU Boulder students return
- •Fall farmers market season
September Tips
- •Pack layers as 70-degree days drop to 40-degree nights
- •Student return creates restaurant waits but adds energy to downtown
- •Trail conditions stay excellent through October
All Months
May through October offers Boulder's best weather, with July and August bringing afternoon thunderstorms that clear quickly. Spring arrives late here – April can still see snow, but wildflowers bloom through June. Summer temperatures hit the 80s during the day and drop to the 50s at night. Perfect hiking weather, but book accommodations early as this is peak season. Fall delivers Boulder's most spectacular scenery. Aspen trees turn gold in the surrounding mountains, and September offers warm days with cool nights. October brings the first snow to high peaks but valley hiking remains excellent. Winter transforms Boulder into a different city. The town gets about 90 inches of snow annually, but sunny days melt it quickly on south-facing slopes. Cross-country skiing and snowshoeing replace hiking, and hotel rates drop significantly. January through March see temperatures ranging from 20-50°F. Spring skiing at nearby resorts runs through April. Avoid major CU football weekends in fall when hotel prices triple and restaurants require reservations weeks in advance.
Boulder Scores
Solo
8/10
Couples
6/10
Families
7/10
Adventure
9/10
Budget
6/10
Luxury
5/10
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