Weather in Boulder in September
Boulder, United States averages a high of 24.2°C (75.6°F) and low of 9.7°C (49.5°F) in September, with 8 rain days and 11.2 hours of daily sunshine. Travel score: 85.2/100 (Excellent). The best time to visit Boulder is August.
High
24°C76°F
Low
10°C49°F
🌧️
8
rain days
☀️
11.2
hrs/day sunshine
💧
54%
humidity
85— Excellent
September in Boulder is warm and occasionally wet — ideal for sightseeing and outdoor activities.
What are the average temperatures in Boulder?
How much does it rain in Boulder in September?
Boulder receives an average of 47.1mm of rainfall across 8 rainy days in September. The annual total is 586.4mm.
What should I pack for Boulder in September?
Essentials
👟
Comfortable walking shoes
Essential for exploring the city
👕
Light layers and t-shirts
Warm weather around 24°C
🧴
Sunscreen SPF 30+
11 hours of sunshine daily
🕶️
Sunglasses
Protect your eyes from bright sun
Traveling to United States in September?
Don't let a public holiday surprise you — restaurants, shops, and attractions may be closed.
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Data based on 1994–2024 averages · Last updated: 2024-12-31