30-year climate normals

Sumter County Climate and Weather Averages

Hottest month — July

90.2°

average daily high. The coldest month is January, averaging a low of 32.8°F.

Sumter County gets 48.83" of precipitation a year, and 32% of it falls in Jun, Jul, Aug.

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	55.1°	32.8°	3.78"
February	58.5°	35.0°	3.47"
March	66.3°	40.9°	3.67"
April	74.7°	49.6°	3.40"
May	81.2°	57.8°	3.78"
June	87.3°	65.9°	5.05"
July	90.2°	69.6°	5.75"
August	88.5°	68.4°	4.92"
September	83.4°	62.9°	4.36"
October	74.4°	50.9°	3.88"
November	64.8°	40.0°	2.94"
December	57.4°	35.0°	3.83"

Rainfall by month

Precipitation is spread fairly evenly through the year here, with 32% falling in the wettest three months (Jun, Jul, Aug).

January 3.78"

February 3.47"

March 3.67"

April 3.40"

May 3.78"

June 5.05"

July 5.75"

August 4.92"

September 4.36"

October 3.88"

November 2.94"

December 3.83"

Annual total 48.83"

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 1,796

Heating degree days How much heating the climate demands 2,821

Approximate annual cooling cost At 16.18¢/kWh, South Carolina average $291

Approximate annual electric heating cost Lower where heating is gas rather than electric $160

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 Sumter County, where electricity is one line of eight.

Common questions

What is the weather like in Sumter County?

Sumter County averages a high of 90.2°F in July and a low of 32.8°F in January. Annual precipitation is 48.83 inches, with essentially no snow.

When is the rainy season in Sumter County?

The wettest stretch is Jun, Jul, Aug, which accounts for 32% of the year's precipitation. Precipitation is relatively evenly distributed across the year.

How hot does it get in Sumter County?

The average daily high in July, the hottest month, is 90.2°F. That drives 1,796 cooling degree days a year, which is what your air conditioning has to work against.

Does it snow in Sumter County?

Effectively no. Measurable snowfall is rare in Sumter County.

Sources

Temperature, precipitation and snowfall normals — NOAA National Centers for Environmental Information, 1991–2020 Monthly Climate Normals, station SUMTER, SC US (USC00388440), 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 Carolina residential average.
Wet-season share is the wettest three consecutive months as a percentage of annual precipitation, calculated from the monthly normals.