Boulder Average Rainfall by Month

This page shows the average precipitation (including snowfall) in each month of the year in Boulder, Colorado. It is based on NOAA data for the years 1991–2020.

Average temperature by month

What's the Rainiest Month in Boulder?

In Boulder, May has the greatest precipitation of any month. On average, Boulder gets 3.2 inches of precipitation in May.

May is also the month where rain is most common. 40.7% of days in May will have at least some rain or snow.

What's the Driest Month in Boulder?

In Boulder, January has the least precipitation of any month. On average, Boulder gets 0.77 inches of precipitation in January.

January is also the month where rain is least common. 18.7% of days in January will have measurable rain or snow.

Month	Precipitation	% Chance
January	0.77 in	18.7
February	0.99 in	24.1
March	1.99 in	26.1
April	3.05 in	33.7
May	3.20 in	40.7
June	1.94 in	33.8
July	1.83 in	34.2
August	1.70 in	33.8
September	2.09 in	26.3
October	1.62 in	23.0
November	1.18 in	19.8
December	0.81 in	17.3
Year	20.97 in	27.6

Weather Station Details

Years	Station	Coordinates
1893–2024	Boulder	location