Climate and average weather in Sumter
In Sumter, the summers are muggy, hot, wet, and partly cloudy and the winters are cool and partly cloudy.
Over the course of the year, the temperature in Sumter typically varies from 37°F to 91°F, and is rarely below 24°F or above 98°F. July is the hottest month of the year, while January is the coldest.
Based on the travel score, the best times of year to visit Sumter for warm-weather activities are from early March to mid May and late September to late November.
- Hottest
- Jul
- 91°
- Coldest
- Jan
- 37°
- Wettest
- Aug
- 4.7 in
- Driest
- Nov
- 2.8 in
- Rain / yr
- 44.3 in
- 121 wet days
- Daylight
- 9.7–14.3 h
- shortest–longest
- Elevation
- 171 ft
- 33.9°N
- Clearest
- Oct
- 46% cloud
Sumter is city in and county seat of Sumter County, South Carolina, United States.
- Density
- 491/km²
- people per km²
- Founded
- 1845
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Sumter weather by month, at a glance
The whole year in one picture — sky, rain, humidity, temperature and travel score. Click any band to jump to its full chart.
Each stripe is one measure across the whole year, stacked so a single day reads top to bottom. The sky band runs overcast grey on top down to clear blue at the base — more blue means sunnier — followed by the rainfall curve, the humidity band, a temperature strip that tints each stretch of the year by how warm its average high is, and the travel-score line at the foot. Scan straight down any date to read that day across every measure at once; the score climbs highest around early March to mid May.
Temperature through the year
Daily average highs and lows in Sumter, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
The hot season lasts 4.3 months, from May 16 to September 22, with daily high temperatures above 82°F. The hottest month of the year in Sumter is July, with an average high of 91°F and low of 74°F.
The cool season lasts 3.0 months, from November 28 to February 27, with daily high temperatures below 63°F. The coldest month of the year in Sumter is January, with an average low of 37°F and high of 56°F.
Days typically run about 19°F warmer than nights year-round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 56 | 60 | 67 | 76 | 82 | 88 | 91 | 89 | 84 | 75 | 66 | 59 |
| Avg low (°F) | 37 | 40 | 46 | 54 | 63 | 71 | 74 | 73 | 67 | 56 | 45 | 40 |
| Avg high (°F) | Avg low (°F) | |
|---|---|---|
| Jan | 56 | 37 |
| Feb | 60 | 40 |
| Mar | 67 | 46 |
| Apr | 76 | 54 |
| May | 82 | 63 |
| Jun | 88 | 71 |
| Jul | 91 | 74 |
| Aug | 89 | 73 |
| Sep | 84 | 67 |
| Oct | 75 | 56 |
| Nov | 66 | 45 |
| Dec | 59 | 40 |
How hot and cold Sumter really feels
The felt-temperature range through the year — heat index on the day's high (summer humidity), wind chill on the night's low (winter wind). The dashed lines are the plain thermometer; the gap is how much hotter or colder it really feels.
On the hottest afternoons, once humidity is folded in, Sumter feels like about 97°F (around July 20). About 86 days a year carry some heat stress, peaking in July.
On the coldest nights, wind chill pulls the feels-like down to about 30°F (around January 22), with roughly 28 freezing days a year (feels-like at or below 32°F), worst in January.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Feels-like high (°F) | 56 | 60 | 67 | 76 | 82 | 91 | 97 | 94 | 86 | 75 | 66 | 59 |
| Air high (°F) | 56 | 60 | 67 | 76 | 82 | 88 | 91 | 89 | 84 | 75 | 66 | 59 |
| Feels-like low (°F) | 31 | 34 | 42 | 54 | 63 | 70 | 74 | 73 | 67 | 55 | 41 | 34 |
| Air low (°F) | 37 | 40 | 46 | 54 | 63 | 71 | 74 | 73 | 67 | 56 | 45 | 40 |
| Feels-like high (°F) | Air high (°F) | Feels-like low (°F) | Air low (°F) | |
|---|---|---|---|---|
| Jan | 56 | 56 | 31 | 37 |
| Feb | 60 | 60 | 34 | 40 |
| Mar | 67 | 67 | 42 | 46 |
| Apr | 76 | 76 | 54 | 54 |
| May | 82 | 82 | 63 | 63 |
| Jun | 91 | 88 | 70 | 71 |
| Jul | 97 | 91 | 74 | 74 |
| Aug | 94 | 89 | 73 | 73 |
| Sep | 86 | 84 | 67 | 67 |
| Oct | 75 | 75 | 55 | 56 |
| Nov | 66 | 66 | 41 | 45 |
| Dec | 59 | 59 | 34 | 40 |
Average hourly temperature in Sumter
A compact picture of the whole year, hour by hour: each column is a day, each row an hour, and the color is the modeled average temperature. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
Read left to right for the day of the year and top to bottom for the hour of the day; the color is the modeled temperature, cool blues through to hot reds on the same scale as the other charts. A vertical slice is a single day's swing — coolest just before dawn, warmest in the mid-afternoon — while a horizontal slice follows one hour across the seasons. The darker overlay marks night and the lighter one the twilight around sunrise and sunset. Colors run warmest on July afternoons, near 91°F, and coldest before dawn in January, near 37°F.
Sumter weather by month
Every month at a glance. Click a month for its detailed page.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 56° / 37° | 3.5 | 8.9 | 0.5 | 10 | 4.1 |
| Feb | 60° / 40° | 3.3 | 8.6 | 0.3 | 10.7 | 4.9 |
| Mar | 67° / 46° | 3.4 | 9.4 | 0.1 | 11.7 | 6.4 |
| Apr | 76° / 54° | 3.4 | 8 | 0 | 12.8 | 7.2 |
| May | 82° / 63° | 3.1 | 9.5 | 0 | 13.7 | 6.2 |
| Jun | 88° / 71° | 4.2 | 13.2 | 0 | 14.2 | 4.1 |
| Jul | 91° / 74° | 4.7 | 15.5 | 0 | 14 | 3.2 |
| Aug | 89° / 73° | 4.7 | 14.5 | 0 | 13.3 | 3.7 |
| Sep | 84° / 67° | 4.2 | 10 | 0 | 12.2 | 5.6 |
| Oct | 75° / 56° | 3.3 | 7.6 | 0 | 11.1 | 7.4 |
| Nov | 66° / 45° | 2.8 | 7.2 | 0 | 10.2 | 6.6 |
| Dec | 59° / 40° | 3.7 | 8.6 | 0.1 | 9.8 | 4.7 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Sumter gets about 44.3 in of precipitation a year. On a typical day the chance of rain is often wet, but that rises and falls sharply with the seasons.
The wetter season lasts 3.7 months, from around May 23 to Sep 13, peaking in July at about 53% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Oct 26.
August is the wettest month by volume, with 4.7 in over about 15 wet days; November is the driest, with 2.8 in.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 28 | 31 | 29 | 27 | 31 | 43 | 50 | 47 | 33 | 25 | 24 | 28 |
| Rain days | 9 | 9 | 9 | 8 | 10 | 13 | 16 | 15 | 10 | 8 | 7 | 9 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 28 | 9 |
| Feb | 31 | 9 |
| Mar | 29 | 9 |
| Apr | 27 | 8 |
| May | 31 | 10 |
| Jun | 43 | 13 |
| Jul | 50 | 16 |
| Aug | 47 | 15 |
| Sep | 33 | 10 |
| Oct | 25 | 8 |
| Nov | 24 | 7 |
| Dec | 28 | 9 |
Monthly rainfall
Over a full year, Sumter collects about 44.3 in of rain across 121 wet days — roughly 3.7 in in an average month.
It doesn’t fall evenly. August is the wettest month with 4.7 in, while November is the driest at just 2.8 in. The three wettest months alone bring about 31% of the year’s total, and some of the cold-season precipitation falls as snow.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (in) | 3.5 | 3.3 | 3.4 | 3.4 | 3.1 | 4.2 | 4.7 | 4.7 | 4.2 | 3.3 | 2.8 | 3.7 |
| Rain days | 9 | 9 | 9 | 8 | 10 | 13 | 16 | 15 | 10 | 8 | 7 | 9 |
| Snow days | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Rainfall (in) | Rain days | Snow days | |
|---|---|---|---|
| Jan | 3.5 | 9 | 1 |
| Feb | 3.3 | 9 | 0 |
| Mar | 3.4 | 9 | 0 |
| Apr | 3.4 | 8 | 0 |
| May | 3.1 | 10 | 0 |
| Jun | 4.2 | 13 | 0 |
| Jul | 4.7 | 16 | 0 |
| Aug | 4.7 | 15 | 0 |
| Sep | 4.2 | 10 | 0 |
| Oct | 3.3 | 8 | 0 |
| Nov | 2.8 | 7 | 0 |
| Dec | 3.7 | 9 | 0 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Sumter, the average share of the sky covered by clouds shows moderate seasonal variation over the course of the year.
The clearer part of the year begins around September 4 and lasts for 3.0 months, ending around December 3. The clearest month is October, when the sky is clear, mostly clear, or partly cloudy 60% of the time on average.
The cloudier part of the year begins around January 21 and lasts for 1.4 months, ending around March 5. The cloudiest month is February, when it is overcast or mostly cloudy 53% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 50 | 47 | 52 | 54 | 55 | 50 | 49 | 50 | 54 | 60 | 58 | 49 |
| Cloudier (%) | 50 | 53 | 48 | 46 | 45 | 50 | 51 | 50 | 46 | 40 | 42 | 51 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 50 | 50 |
| Feb | 47 | 53 |
| Mar | 52 | 48 |
| Apr | 54 | 46 |
| May | 55 | 45 |
| Jun | 50 | 50 |
| Jul | 49 | 51 |
| Aug | 50 | 50 |
| Sep | 54 | 46 |
| Oct | 60 | 40 |
| Nov | 58 | 42 |
| Dec | 49 | 51 |
Daylight, sunrise and sunset
Hours of daylight through the year, with sunrise and sunset times.
The gold band is daylight — sunrise runs along its lower edge, sunset along the upper — so it widens toward summer and pinches toward winter, with night the dark area above and below. The longest day, around June 18, brings about 14 h 18 min of light; the shortest, around December 17, only 9 h 42 min — a swing of roughly 4 h 36 min.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 10.0 | 10.7 | 11.7 | 12.8 | 13.7 | 14.2 | 14.0 | 13.3 | 12.2 | 11.1 | 10.2 | 9.8 |
| Sunrise (AM) | 7:31 | 7:14 | 6:39 | 5:56 | 5:25 | 5:14 | 5:25 | 5:47 | 6:09 | 6:32 | 7:00 | 7:25 |
| Sunset (PM) | 5:30 | 5:58 | 6:23 | 6:47 | 7:10 | 7:29 | 7:29 | 7:04 | 6:22 | 5:41 | 5:13 | 5:10 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 10.0 | 7:31 | 5:30 |
| Feb | 10.7 | 7:14 | 5:58 |
| Mar | 11.7 | 6:39 | 6:23 |
| Apr | 12.8 | 5:56 | 6:47 |
| May | 13.7 | 5:25 | 7:10 |
| Jun | 14.2 | 5:14 | 7:29 |
| Jul | 14.0 | 5:25 | 7:29 |
| Aug | 13.3 | 5:47 | 7:04 |
| Sep | 12.2 | 6:09 | 6:22 |
| Oct | 11.1 | 6:32 | 5:41 |
| Nov | 10.2 | 7:00 | 5:13 |
| Dec | 9.8 | 7:25 | 5:10 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Sumter averages about 11 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 7 and 15 days.
The sunnier stretch runs 4.7 months, from around Sep 14 to Feb 4. The sunniest month is October, with roughly 14 sunny days (mixed).
The greyest month is July, down near 7 sunny days — about 49% fewer than the October peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 12 | 10 | 12 | 11 | 11 | 8 | 8 | 9 | 11 | 15 | 14 | 12 |
| Sky | Mixed | Mixed | Mixed | Mixed | Mixed | Mixed | Gloomy | Mixed | Mixed | Mixed | Mixed | Mixed |
| Sunny days | Sky | |
|---|---|---|
| Jan | 12 | Mixed |
| Feb | 10 | Mixed |
| Mar | 12 | Mixed |
| Apr | 11 | Mixed |
| May | 11 | Mixed |
| Jun | 8 | Mixed |
| Jul | 8 | Gloomy |
| Aug | 9 | Mixed |
| Sep | 11 | Mixed |
| Oct | 15 | Mixed |
| Nov | 14 | Mixed |
| Dec | 12 | Mixed |
Humidity comfort
Share of days at each humidity comfort level, based on the dew point — the measure that tracks how muggy it actually feels.
Humidity comfort is graded by the dew point — the temperature at which the air would be fully saturated — because it tracks how muggy it actually feels far better than relative humidity does. A low dew point feels dry and crisp; a high one feels sticky and oppressive no matter the reading on a humidity gauge.
In Sumter, how humid it feels changes dramatically over the year.
The more humid part of the year lasts 5.1 months, from around May 10 to October 10. The muggiest month is July, when the air feels humid, muggy or worse about 97% of the time.
The most comfortable stretch runs from around October 11 to May 9, and January is the most comfortable month — the air is dry or comfortable 97% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 92 | 92 | 82 | 64 | 31 | 5 | 1 | 1 | 12 | 49 | 80 | 89 |
| Comfortable (%) | 5 | 6 | 12 | 19 | 19 | 8 | 2 | 2 | 12 | 17 | 9 | 7 |
| Humid (%) | 2 | 2 | 6 | 13 | 24 | 17 | 7 | 9 | 19 | 18 | 8 | 3 |
| Muggy (%) | 1 | 0 | 0 | 4 | 21 | 36 | 25 | 24 | 29 | 12 | 2 | 1 |
| Oppressive (%) | 0 | 0 | 0 | 0 | 5 | 33 | 61 | 58 | 27 | 4 | 0 | 0 |
| Miserable (%) | 0 | 0 | 0 | 0 | 0 | 0 | 4 | 5 | 1 | 0 | 0 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | Oppressive (%) | Miserable (%) | |
|---|---|---|---|---|---|---|
| Jan | 92 | 5 | 2 | 1 | 0 | 0 |
| Feb | 92 | 6 | 2 | 0 | 0 | 0 |
| Mar | 82 | 12 | 6 | 0 | 0 | 0 |
| Apr | 64 | 19 | 13 | 4 | 0 | 0 |
| May | 31 | 19 | 24 | 21 | 5 | 0 |
| Jun | 5 | 8 | 17 | 36 | 33 | 0 |
| Jul | 1 | 2 | 7 | 25 | 61 | 4 |
| Aug | 1 | 2 | 9 | 24 | 58 | 5 |
| Sep | 12 | 12 | 19 | 29 | 27 | 1 |
| Oct | 49 | 17 | 18 | 12 | 4 | 0 |
| Nov | 80 | 9 | 8 | 2 | 0 | 0 |
| Dec | 89 | 7 | 3 | 1 | 0 | 0 |
Wind
Average wind speed through the year, banded into plain-language speed zones so a number reads as 'breezy' or 'calm' without knowing the scale.
This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.
Across the year, average wind speed in Sumter is typically calm, near 7 mph, and varies little with the seasons.
The windier part of the year lasts 6.2 months, from around Nov 9 to May 16. The windiest month is April, averaging about 8 mph (light breeze).
The calmer part of the year runs from around May 17 to Nov 8, with August the calmest month at about 6 mph.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (mph) | 8 | 8 | 8 | 8 | 7 | 6 | 6 | 6 | 7 | 7 | 7 | 8 |
| Feels | light breeze | light breeze | light breeze | light breeze | calm | calm | calm | calm | calm | calm | calm | light breeze |
| Wind speed (mph) | Feels | |
|---|---|---|
| Jan | 8 | light breeze |
| Feb | 8 | light breeze |
| Mar | 8 | light breeze |
| Apr | 8 | light breeze |
| May | 7 | calm |
| Jun | 6 | calm |
| Jul | 6 | calm |
| Aug | 6 | calm |
| Sep | 7 | calm |
| Oct | 7 | calm |
| Nov | 7 | calm |
| Dec | 8 | light breeze |
Best time to visit Sumter
To characterize how pleasant the weather is in Sumter throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around mid May, Sumter is still near the tail of its best-weather window — great conditions with the peak-season crowds already thinning.
Inferred from the travel-score curve; month-by-month visitor numbers are a planned addition.
The travel score favors clear, rainless days with daytime highs between 64°F and 82°F. Based on this score, the best times of year to visit Sumter for general outdoor tourist activities run from early March to mid May and again from late September to late November, with a peak score in the third week of October.
The travel score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Travel score (0–10) | 4.1 | 4.9 | 6.4 | 7.2 | 6.1 | 4.1 | 3.3 | 3.7 | 5.6 | 7.3 | 6.6 | 4.7 |
| Rating | fair | fair | good | good | good | fair | poor | fair | good | good | good | fair |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 4.1 | fair |
| Feb | 4.9 | fair |
| Mar | 6.4 | good |
| Apr | 7.2 | good |
| May | 6.1 | good |
| Jun | 4.1 | fair |
| Jul | 3.3 | poor |
| Aug | 3.7 | fair |
| Sep | 5.6 | good |
| Oct | 7.3 | good |
| Nov | 6.6 | good |
| Dec | 4.7 | fair |
The beach/pool score favors clear, rainless days with daytime highs between 75°F and 93°F. Based on this score, the best times of year to visit Sumter for hot-weather activities run from early April to mid July and again from early August to late October, with a peak score in the third week of May.
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
What to pack for Sumter, by month
Month by month, what's worth putting in the bag — from the temperature range, rain chance, sun and wind. Tap a month for a quick packing note.
For a warm-season trip around July (highs near 91°F), the essentials are light clothes, rain gear and sun protection. In the cold season around January (highs near 56°F), pack a warm layer and rain gear.
In July, Sumter sees daytime highs around 91°F and nights near 74°F. Pack light clothes, rain gear and sun protection. About 16 days see rain.
UV index (midday) in Sumter by month
Clear-sky midday UV index through the year, shaded by the WHO exposure levels — how much sun protection each month calls for.
Under clear skies, the midday UV index in Sumter peaks around July 13 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 20 at about 3 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 11 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 3 | 5 | 6 | 7 | 8 | 9 | 9 | 8 | 7 | 5 | 4 | 3 |
| Level | Moderate | Moderate | High | High | Very high | Very high | Very high | Very high | Very high | Moderate | Moderate | Moderate |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 3 | Moderate |
| Feb | 5 | Moderate |
| Mar | 6 | High |
| Apr | 7 | High |
| May | 8 | Very high |
| Jun | 9 | Very high |
| Jul | 9 | Very high |
| Aug | 8 | Very high |
| Sep | 7 | Very high |
| Oct | 5 | Moderate |
| Nov | 4 | Moderate |
| Dec | 3 | Moderate |
Average hourly UV index in Sumter
Modeled clear-sky UV for every hour of every day — when in the day sun protection actually matters.
The whole year hour by hour: each column is a day, each row an hour, and the color is the modeled clear-sky UV index — the midday peak scaled down as the sun sits lower in the sky. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
UV falls off far faster than brightness as the sun drops, so even in July the burn window is concentrated in the middle of the day: about 8 hours a day reach index 3 (protection recommended), and 5.5 hours reach 6 or more. Mornings and late afternoons stay comparatively gentle year round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV ≥ 3 (h/day) | 2 | 4 | 6 | 6.5 | 8 | 8 | 8 | 7.5 | 6.5 | 5 | 3.5 | 0 |
| UV ≥ 6 (h/day) | 0 | 0 | 1.5 | 3 | 4.5 | 5 | 5.5 | 4.5 | 3.5 | 0 | 0 | 0 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 2 | 0 |
| Feb | 4 | 0 |
| Mar | 6 | 1.5 |
| Apr | 6.5 | 3 |
| May | 8 | 4.5 |
| Jun | 8 | 5 |
| Jul | 8 | 5.5 |
| Aug | 7.5 | 4.5 |
| Sep | 6.5 | 3.5 |
| Oct | 5 | 0 |
| Nov | 3.5 | 0 |
| Dec | 0 | 0 |
Air quality in Sumter by month
Average fine-particle pollution (PM2.5) through the year — so you can see which months the air is worst, not just the yearly average.
Air quality in Sumter is worst in March — around 18 µg/m³ PM2.5 (moderate), about 2.3× the cleanest month (December, 8 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 8 | 11 | 18 | 13 | 13 | 17 | 18 | 16 | 12 | 9 | 8 | 8 |
| Level | Good | Good | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 8 | Good |
| Feb | 11 | Good |
| Mar | 18 | Moderate |
| Apr | 13 | Moderate |
| May | 13 | Moderate |
| Jun | 17 | Moderate |
| Jul | 18 | Moderate |
| Aug | 16 | Moderate |
| Sep | 12 | Good |
| Oct | 9 | Good |
| Nov | 8 | Good |
| Dec | 8 | Good |
Growing season
Sumter is mild enough that a frost-free day stays more likely than not even in midwinter. Nights are reliably above freezing from about March 14 to November 16 (248 days); outside that window a hard frost is an occasional risk.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 69 | 78 | 92 | 99 | 100 | 100 | 100 | 100 | 100 | 99 | 90 | 77 |
| Frost nights | 31 | 28 | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 11 | 31 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 69 | 31 |
| Feb | 78 | 28 |
| Mar | 92 | 13 |
| Apr | 99 | 0 |
| May | 100 | 0 |
| Jun | 100 | 0 |
| Jul | 100 | 0 |
| Aug | 100 | 0 |
| Sep | 100 | 0 |
| Oct | 99 | 0 |
| Nov | 90 | 11 |
| Dec | 77 | 31 |
Growing degree days
Growing degree days tally heat above 50°F: each day adds however many degrees its average temperature runs over that threshold, and cold days add nothing. Sumter banks about 5,613 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around July.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°F·days) | 0 | 18 | 201 | 448 | 700 | 878 | 1,001 | 957 | 762 | 476 | 163 | 8 |
| Growing degree days (°F·days) | |
|---|---|
| Jan | 0 |
| Feb | 18 |
| Mar | 201 |
| Apr | 448 |
| May | 700 |
| Jun | 878 |
| Jul | 1,001 |
| Aug | 957 |
| Sep | 762 |
| Oct | 476 |
| Nov | 163 |
| Dec | 8 |
Solar energy
Average daily shortwave solar energy reaching the ground, banded into brightness zones so the number means something at a glance.
Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.
Sumter receives about 4.5 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 2.4 and 6.2 kWh/m².
The brighter stretch of the year lasts 6.2 months, from around Mar 14 to Sep 18. The brightest month is June, averaging about 6.2 kWh/m² (intense).
The dimmest month is December, down near 2.4 kWh/m² — roughly 61% less than the June peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 2.7 | 3.4 | 4.5 | 5.8 | 6.2 | 6.2 | 6.1 | 5.4 | 4.6 | 3.9 | 3.0 | 2.4 |
| Level | Moderate | Moderate | Bright | Bright | Intense | Intense | Intense | Bright | Bright | Moderate | Moderate | Moderate |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 2.7 | Moderate |
| Feb | 3.4 | Moderate |
| Mar | 4.5 | Bright |
| Apr | 5.8 | Bright |
| May | 6.2 | Intense |
| Jun | 6.2 | Intense |
| Jul | 6.1 | Intense |
| Aug | 5.4 | Bright |
| Sep | 4.6 | Bright |
| Oct | 3.9 | Moderate |
| Nov | 3.0 | Moderate |
| Dec | 2.4 | Moderate |
Where is Sumter?
Sumter sits at 33.9°N, 80.3°W, 171 ft above sea level, in United States. The nearest listed city is Florence, 38 mi away.
Topography around Sumter
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Sumter.
Within 2 miles, the terrain around Sumter has only modest variations in elevation — a maximum elevation change of 98 ft around an average of 171 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 305 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 1,079 ft.
The land around Sumter is covered by trees (63%) and artificial surfaces (25%) within 2 miles, trees (64%) within 10 miles, and trees (75%) within 50 miles.
United States travel facts
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 100% of US
- price level, 2025
- GDP per capita
- $90,027
- 2025
- Happiness
- 6.8 / 10
- World Happiness, 2025
- Safe drinking water
- 98%
- of population, 2024
- Homicide rate
- 5.8
- per 100k, 2023
- Road deaths
- 12.7
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Sumter (33.9204°, -80.3415°, elevation 171 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).