30-year climate normals

Jefferson County Climate and Weather Averages

Hottest month — July

81.2°

average daily high. The coldest month is January, averaging a low of 12.5°F.

Jefferson County gets 18.62" of precipitation a year and 80.8" of snow, 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	Snow
January	44.4°	12.5°	0.63"	8.8"
February	44.4°	13.4°	0.86"	11.4"
March	51.0°	20.9°	1.76"	17.0"
April	55.6°	26.7°	2.37"	14.9"
May	64.0°	35.5°	2.49"	2.7"
June	75.6°	43.1°	1.73"	0.0"
July	81.2°	49.0°	2.20"	0.0"
August	79.1°	47.2°	2.30"	0.0"
September	72.5°	39.5°	1.55"	1.1"
October	61.1°	28.7°	1.21"	6.5"
November	51.1°	20.2°	0.81"	10.4"
December	44.0°	12.6°	0.71"	8.0"

Rainfall by month

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

January 0.63"

February 0.86"

March 1.76"

April 2.37"

May 2.49"

June 1.73"

July 2.20"

August 2.30"

September 1.55"

October 1.21"

November 0.81"

December 0.71"

Annual total 18.62"

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 99

Heating degree days How much heating the climate demands 7,467

Approximate annual cooling cost At 16.16¢/kWh, Colorado average $16

Approximate annual electric heating cost Lower where heating is gas rather than electric $422

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 Jefferson County, where electricity is one line of eight.

Common questions

What is the weather like in Jefferson County?

Jefferson County averages a high of 81.2°F in July and a low of 12.5°F in January. Annual precipitation is 18.62 inches, including 80.8 inches of snow.

When is the rainy season in Jefferson 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 Jefferson County?

The average daily high in July, the hottest month, is 81.2°F. That drives 99 cooling degree days a year, which is what your air conditioning has to work against.

Does it snow in Jefferson County?

Yes. Jefferson County averages 80.8 inches of snow a year.

Sources

Temperature, precipitation and snowfall normals — NOAA National Centers for Environmental Information, 1991–2020 Monthly Climate Normals, station EVERGREEN, CO US (USC00052790), 5.5 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.