Boulder Weather in October

The climate in Boulder during October can be summarized as mild and reasonably dry.

October is in the fall / autumn in Boulder and is typically the 6th warmest month of the year. Daytime maximum temperatures average around a cool 18°C (65°F), whilst at night 2°C (36°F) is normal.

On average October is the 4th driest month of the year in Boulder with around 31mm 1.2 inches of rain making it a reasonably dry time to visit. This rainfall is typically spread over 5 days, although this may vary considerably.

On the flip side this corresponds to an average of 8.6 hours of sunshine per day.

The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Boulder in October 2025.