Boulder (CO) Sunshine Hours by Month

The amount of sunshine is fundamental to comprehending a place's climate. This page shows the total number of hours of direct sunlight per month and the average hours per day in Boulder, Colorado, United States of America. These values are calculated using 30 years of data (1990–2020) to ensure accuracy.

Monthly hours of sunshine

Seasonal sunshine in Boulder varies. It peaks at 323 hours in July and drops to 195 hours in November. The total annual amount of sun is 3102 hours.

Daily hours of sunshine

In Boulder, summer days are longer and more sunny, with daily sunshine hours peaking at 10.8 hours in July. As the darker season arrives, the brightness of the sun becomes less. November sees a soft sun for only 6.5 hours per day.

Average percent of sunshine

On average the sun shines 73% of the time during the day in September, the highest percentage of any month. May has the lowest percentage at 65%.

Boulder enjoys an average of 3102 hours of sunshine annually. Let’s compare this with some popular tourist destinations:

In Barcelona, Spain, there are 2530 hours of sunshine annually and is a city that can be visited year-round.

In contrast, Brussels, Belgium, receives only about 1590 hours of sunshine per year, known for its frequently overcast and rainy skies.

Boston, USA, enjoys 2629 hours of sunshine annually, with distinct seasons and many bright, sunny days.

Melbourne, Australia, has 2380 hours of sunshine annually, with its famous “four seasons in a day” weather pattern.

May, Boulder’s wettest month, receives 53 mm (2.1 in) of rainfall and has a maximum daytime temperature of 21°C (70°F). During the driest month January you can expect a temperature of 8°C (46°F).

For more detailed insights into the city’s temperatures, check out our Temperature page. To explore more about precipitation patterns, visit our Boulder Precipitation page.