Sumter climate — normals and trends
Sumter (United States) has a humid subtropical climate (Cfa) under the Köppen-Geiger classification. Its mean annual temperature is 17.7 °C and it receives 1,098 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (27.0 °C on average) and the coldest is January (7.6 °C). Rainfall peaks in July.
Sumter averages 31 frost days, 91 hot days (≥ 30 °C) and 123 rainy days per year.
Sumter has warmed by +1.2 °C between 1940 and 2025, or +0.14 °C per decade. This trend is statistically significant.
The hottest day of the period reached 41.8 °C (on 29 June 2012) and the coldest -16.0 °C (on 21 January 1985).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
SumterSouth Carolina
- coords
- 33.92°, -80.34°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
17.7°C
Average daily high
23.3°C
Average daily low
12.8°C
Annual rainfall
1,098mm
Sunshine / day
9.3h
Mean relative humidity
69%
Average peak wind
17.7km/h
Seasonal range
19.4°C
Frost days (< 0 °C)
31 d/yr
Hot days (≥ 30 °C)
91 d/yr
Rainy days (≥ 1 mm)
123 d/yr
Annual snowfall
3.9 cm
Average feels-like high
23.3 °C
Average feels-like low
11.8 °C
Average peak gust
35.4 km/h
Tropical nights (≥ 20 °C)
103 d/yr
Solar radiation
16.3 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.2 °C
since 1940
+0.1 °C per decade · r² = 0.26 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
41.8 °C
29 June 2012
Coldest day
-16.0 °C
21 January 1985
Wettest day
151 mm
8 October 2016
Windiest day
91.9 km/h
22 September 1989
Strongest gust
176.8 km/h
22 September 1989
Hottest feels-like
45.5 °C
21 August 1983
Coldest feels-like
-22.6 °C
21 January 1985
Snowiest day
25.7 cm
10 February 1973
Sunniest day
13.9 h
19 June 2022
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 11.1 °C | -2.1 °C | 45 mm | -40 mm |
| Feb | 18.0 °C | +2.8 °C | 32 mm | -56 mm |
| Mar | 22.7 °C | +3.6 °C | 74 mm | -22 mm |
| Apr | 26.3 °C | +2.3 °C | 61 mm | -18 mm |
| May | 28.2 °C | +0.4 °C | 127 mm | +48 mm |
| Jun | 33.1 °C | +2.2 °C | 74 mm | -29 mm |
| Jul | 34.5 °C | +2.4 °C | 120 mm | -9 mm |
| Aug | 29.5 °C | -1.8 °C | 140 mm | +17 mm |
| Sep | 30.6 °C | +1.9 °C | 45 mm | -55 mm |
| Oct | 22.8 °C | -1.1 °C | 177 mm | +106 mm |
| Nov | 20.9 °C | +1.9 °C | 11 mm | -54 mm |
| Dec | 14.5 °C | 0.0 °C | 67 mm | -15 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Sumter?
Sumter has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 17.7 °C and it receives 1,098 mm of precipitation per year.
What is the hottest day ever recorded in Sumter?
The hottest day measured in Sumter between 1940 and 2025 was 29 June 2012, reaching 41.8 °C.
What is the coldest day in Sumter?
The coldest day measured in Sumter between 1940 and 2025 was 21 January 1985, at -16.0 °C.
Does it snow in Sumter?
Yes. Sumter gets on average 3.9 cm of snow per year and has around 31 frost days.
Has the climate of Sumter warmed?
Yes: Sumter warmed by +1.2 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Sumter?
The wettest day measured in Sumter between 1940 and 2025 was 8 October 2016, with 151 mm of rain in 24 hours.
What was the windiest day in Sumter?
The windiest day measured in Sumter between 1940 and 2025 was 22 September 1989, with winds reaching 91.9 km/h.
What is the warmest month in Sumter?
The warmest month in Sumter is July (27.0 °C on average); the coldest is January (7.6 °C).
How much does it rain in Sumter?
Sumter receives on average 1,098 mm of precipitation per year, spread over about 123 rainy days.
Is it sunny in Sumter?
Sumter gets on average 9.3 hours of sunshine per day, roughly 3,395 hours per year over 1940-2025.
What is the biggest single-day snowfall in Sumter?
The heaviest 24-hour snowfall measured in Sumter between 1940 and 2025 was 10 February 1973, with 25.7 cm.
Are there tropical nights in Sumter?
Yes: Sumter has on average 103 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Sumter?
In Sumter, between 1940 and 2025, the highest apparent temperature reached 45.5 °C on 21 August 1983, and the lowest was -22.6 °C on 21 January 1985.
Compare Sumter with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Sumter