30-year climate normals

Custer County Climate and Weather Averages

Hottest month — July

79.2°

average daily high. The coldest month is January, averaging a low of 15.0°F.

Custer County gets 19.75" of precipitation a year, and 48% 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	35.2°	15.0°	0.41"
February	35.2°	15.0°	0.59"
March	43.5°	22.2°	0.91"
April	50.1°	28.5°	2.42"
May	59.6°	37.5°	2.97"
June	71.1°	46.7°	3.16"
July	79.2°	53.7°	3.29"
August	77.8°	51.6°	2.12"
September	69.0°	42.9°	1.59"
October	54.1°	31.8°	1.29"
November	42.9°	22.2°	0.52"
December	34.9°	15.5°	0.48"

Rainfall by month

Custer County has a distinct wet season. 48% of the year's precipitation arrives in May, Jun, Jul.

January 0.41"

February 0.59"

March 0.91"

April 2.42"

May 2.97"

June 3.16"

July 3.29"

August 2.12"

September 1.59"

October 1.29"

November 0.52"

December 0.48"

Annual total 19.75"

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 210

Heating degree days How much heating the climate demands 8,152

Approximate annual cooling cost At 15.73¢/kWh, South Dakota average $33

Approximate annual electric heating cost Lower where heating is gas rather than electric $449

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 Custer County, where electricity is one line of eight.

Common questions

What is the weather like in Custer County?

Custer County averages a high of 79.2°F in July and a low of 15.0°F in January. Annual precipitation is 19.75 inches, with essentially no snow.

When is the rainy season in Custer County?

The wettest stretch is May, Jun, Jul, which accounts for 48% of the year's precipitation. That is a pronounced wet season rather than rain spread evenly through the year.

How hot does it get in Custer County?

The average daily high in July, the hottest month, is 79.2°F. That drives 210 cooling degree days a year, which is what your air conditioning has to work against.

Does it snow in Custer County?

Effectively no. Measurable snowfall is rare in Custer County.

Sources

Temperature, precipitation and snowfall normals — NOAA National Centers for Environmental Information, 1991–2020 Monthly Climate Normals, station CUSTER CO AP, SD US (USW00094032), 8.2 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, South Dakota residential average.
Wet-season share is the wettest three consecutive months as a percentage of annual precipitation, calculated from the monthly normals.