Boulder weather in August
August in Boulder: hot, a little rain, with clean air — one of the best months to visit.
#2 of 12 months in Boulder · #106 of 897 destinations to visit in August · comfort 91/100 (tier S)
Updated June 2026 · climate normals from ERA5 reanalysis
Traveller notes on Boulder in August
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Boulder climate normals — August
| Daytime high | 30°C / 85°F | 🥵 hot |
|---|---|---|
| Nighttime low | 14°C / 58°F | |
| Rainfall | 56 mm / 2.2 in | 🌦 some rain |
| Rainy days | 13 days | |
| Humidity | 57% | 🍃 comfortable |
| Dew point | 11°C / 52°F | |
| Sunshine | 12.2 h/day | |
| Daylight | 13.7 h | |
| Wind | 13 km/h / 8 mph | |
| Air quality (US AQI) | 43 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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Boulder in August — FAQ
- Is August a good time to visit Boulder?
- August in Boulder: hot, a little rain, with clean air — one of the best months to visit. It ranks #2 of 12 months for Boulder on SeasonMap's comfort score (91/100).
- What is the weather like in Boulder in August?
- In August, Boulder averages a daily high of 29.7°C and a low of 14.4°C, with about 55.8 mm of rain over roughly 12.8 rainy days.
- What is the air quality in Boulder in August?
- Boulder has a mean US Air Quality Index of about 43 in August.