30-year climate normals

Loudoun County Climate and Weather Averages

Hottest month — July

86.4°

average daily high. The coldest month is January, averaging a low of 24.5°F.

Loudoun County gets 43.78" of precipitation a year, and 29% of it falls in May, Jun, Jul.

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	41.0°	24.5°	3.05"
February	44.0°	25.9°	2.56"
March	52.6°	32.3°	3.61"
April	64.5°	42.2°	3.54"
May	72.9°	51.6°	4.35"
June	81.4°	61.1°	4.25"
July	86.4°	65.5°	4.08"
August	84.7°	63.9°	3.57"
September	77.8°	56.1°	4.77"
October	66.3°	44.3°	3.52"
November	54.9°	34.5°	3.13"
December	44.7°	28.4°	3.35"

Rainfall by month

Precipitation is spread fairly evenly through the year here, with 29% falling in the wettest three months (May, Jun, Jul).

January 3.05"

February 2.56"

March 3.61"

April 3.54"

May 4.35"

June 4.25"

July 4.08"

August 3.57"

September 4.77"

October 3.52"

November 3.13"

December 3.35"

Annual total 43.78"

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 1,050

Heating degree days How much heating the climate demands 4,943

Approximate annual cooling cost At 17.61¢/kWh, Virginia average $185

Approximate annual electric heating cost Lower where heating is gas rather than electric $305

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 Loudoun County, where electricity is one line of eight.

Common questions

What is the weather like in Loudoun County?

Loudoun County averages a high of 86.4°F in July and a low of 24.5°F in January. Annual precipitation is 43.78 inches, with essentially no snow.

When is the rainy season in Loudoun County?

The wettest stretch is May, Jun, Jul, which accounts for 29% of the year's precipitation. Precipitation is relatively evenly distributed across the year.

How hot does it get in Loudoun County?

The average daily high in July, the hottest month, is 86.4°F. That drives 1,050 cooling degree days a year, which is what your air conditioning has to work against.

Does it snow in Loudoun County?

Effectively no. Measurable snowfall is rare in Loudoun County.

Sources

Temperature, precipitation and snowfall normals — NOAA National Centers for Environmental Information, 1991–2020 Monthly Climate Normals, station PURCELLVILLE, VA US (USC00444909), 5.7 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, Virginia residential average.
Wet-season share is the wettest three consecutive months as a percentage of annual precipitation, calculated from the monthly normals.