30-year climate normals

Boulder County Climate and Weather Averages

Hottest month — July

67.9°

average daily high. The coldest month is February, averaging a low of 11.5°F.

Boulder County gets 33.86" of precipitation a year, and 36% of it falls in Mar, Apr, May.

Temperature through the year

Each bar spans the average daily low to the average daily high for that month.

Month	Avg high	Avg low	Precip
January	28.6°	11.8°	2.67"
February	27.8°	11.5°	2.77"
March	35.6°	16.7°	3.68"
April	40.3°	21.5°	4.83"
May	50.1°	28.6°	3.82"
June	61.8°	35.9°	1.95"
July	67.9°	42.5°	3.04"
August	65.8°	40.8°	2.51"
September	58.5°	33.6°	2.01"
October	46.8°	26.0°	2.17"
November	35.3°	19.1°	2.26"
December	28.0°	11.5°	2.15"

Rainfall by month

Precipitation is spread fairly evenly through the year here, with 36% falling in the wettest three months (Mar, Apr, May).

January 2.67"

February 2.77"

March 3.68"

April 4.83"

May 3.82"

June 1.95"

July 3.04"

August 2.51"

September 2.01"

October 2.17"

November 2.26"

December 2.15"

Annual total 33.86"

What this climate costs you

Degree days measure how hard a building has to work to stay comfortable. They are the reason two identical houses have very different power bills, and they are the link between the weather here and what you pay every month.

Cooling degree days How much air conditioning the climate demands 0

Heating degree days How much heating the climate demands 10,824

Approximate annual cooling cost At 16.16¢/kWh, Colorado average $0

Approximate annual electric heating cost Lower where heating is gas rather than electric $612

These are rough planning figures from degree days and the state electricity price, not a bill estimate. House size, insulation and fuel type move them a lot. See the full cost of owning a home in Boulder County, where electricity is one line of eight.

Common questions

What is the weather like in Boulder County?

Boulder County averages a high of 67.9°F in July and a low of 11.5°F in February. Annual precipitation is 33.86 inches, with essentially no snow.

When is the rainy season in Boulder County?

The wettest stretch is Mar, Apr, May, which accounts for 36% of the year's precipitation. Precipitation is relatively evenly distributed across the year.

How hot does it get in Boulder County?

The average daily high in July, the hottest month, is 67.9°F. That drives 0 cooling degree days a year, which is what your air conditioning has to work against.

Does it snow in Boulder County?

Effectively no. Measurable snowfall is rare in Boulder County.

Sources

Temperature, precipitation and snowfall normals — NOAA National Centers for Environmental Information, 1991–2020 Monthly Climate Normals, station BOULDER 14 W, CO US (USW00094075), 8.6 miles from the county centroid.
Heating and cooling degree days — NOAA, same station and period.
Electricity price — US Energy Information Administration, Electric Power Monthly Table 5.6.A, Colorado residential average.
Wet-season share is the wettest three consecutive months as a percentage of annual precipitation, calculated from the monthly normals.