Sullivans Island, SC Climate: Temperature & Rain by Month
Average temperature and precipitation from NOAA NCEI 1991–2020 normals →, with a derived climate comfort score
30-year climate normals (1991-2020) from Sullivans Island's primary NOAA station, SULLIVANS IS.
The climate verdict for Sullivans Island
Water is the standout signal in Sullivans Island, South Carolina: 51.6 inches of precipitation in a normal year. Against that wet profile, NOAA records an annual average of 66°F. It scores 85/100 for climate comfort (excellent), putting it in the top third of station-mapped location scores and exceeding 85% of them.
- 66°F
- average temperature, NOAA 1991-2020 normal
- 85/100
- comfort score, above 85% of station-mapped location scores
- 51.6"
- precipitation, annual total
- 262 days
- growing season, frost-free days
Sullivans Island: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00388405 · Sullivans Island, SC 66°F mean · 51.6" precip
TEMP-MILD · RANK-UPPER · PHOTO-FINISH · PRCP-WET · SWING-MID · COMF-TOP · LOAD-MIX · STN-1 · BOOK-FULL
- TEMP-MILD 66°F
- RANK-UPPER #6,106
- PHOTO-FINISH ≈ Athens
- PRCP-WET 51.6"
- SWING-MID 34°F
- COMF-TOP 85/100
- LOAD-MIX H/C balanced
- STN-1 USC00388405
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Athens, TX (+ 0 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every SC station list.
- Sullivans Island (this station) 66°F
- Hot Bunkerville, NV 66°F
- Near Athens, TX 66°F
- Near Blanco, TX 66°F
- Near Brewton, AL 66°F
Climate Living Index · Sullivans Island
Sullivans Island: 82/100 · grade B
Sullivans Island publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Sullivans Island, not an official NOAA rating. Rankings still use Comfort Score 85/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Annual temperature balance | 65.5°F · 2.0° from 67.5°F | 93/100 · A |
| Frost-free season | 262 days/year | 92/100 · A |
| Normal heat + freeze calendar | 51 calendar days | 91/100 · A |
| Precipitation balance | 51.6 in · 16.6 from 35 in | 41/100 · D |
Sullivans Island · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Sullivans Island is a temperate Köppen climate: Cfa
Coldest-month mean 47.8°F and warmest-month mean 82.0°F place this station in temperate, no dry season, hot summer climates (Cfa). Class Cfa is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: temperate, specifically temperate, no dry season, hot summer.
- Köppen code
- Cfa
- Group
- Temperate
- Warmest month
- 82.0°F
- Coldest month
- 47.8°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · balanced station
Where Sullivans Island sits across the climate record
Three NOAA fields for Sullivans Island's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Top 11% warmest
- Among 6,861 stations, Sullivans Island sits in the warmer third of annual means.
- Annual precipitation
- Top 16% wettest
- Sullivans Island's annual total ranks in the wetter third of 6,352 measured normals.
- Seasonal temperature swing
- Narrower than 84%
- Warmest-to-coldest month gap for Sullivans Island is compact versus 6,861 complete station-years.
How Sullivans Island compares across U.S. station-mapped locations
Sullivans Island's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
85 Top 15% score exceeds 85% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). Below this entry.
- 50–60: 1,329 station-mapped locations (21%). Below this entry.
- 60–70: 1,236 station-mapped locations (20%). Below this entry.
- 70–80: 650 station-mapped locations (11%). Below this entry.
- 80–90: 921 station-mapped locations (15%). This entry sits in this band.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 59°F (15°C) | 37°F (3°C) | 48°F (9°C) | 3.8" | 7.7 | 0.0 |
| February | 61°F (16°C) | 39°F (4°C) | 50°F (10°C) | 3.3" | 4.2 | 0.0 |
| March | 67°F (19°C) | 45°F (7°C) | 56°F (13°C) | 3.5" | 1.2 | 0.0 |
| April | 75°F (24°C) | 54°F (12°C) | 64°F (18°C) | 3.6" | 0.1 | 0.3 |
| May | 82°F (28°C) | 63°F (17°C) | 73°F (23°C) | 3.3" | 0.0 | 2.2 |
| June | 88°F (31°C) | 70°F (21°C) | 79°F (26°C) | 5.4" | 0.0 | 10.4 |
| July | 91°F (33°C) | 73°F (23°C) | 82°F (28°C) | 6.0" | 0.0 | 19.0 |
| August | 90°F (32°C) | 72°F (22°C) | 81°F (27°C) | 6.7" | 0.0 | 16.1 |
| September | 86°F (30°C) | 68°F (20°C) | 77°F (25°C) | 5.5" | 0.0 | 6.4 |
| October | 78°F (26°C) | 58°F (14°C) | 68°F (20°C) | 3.9" | 0.0 | 0.5 |
| November | 69°F (21°C) | 47°F (8°C) | 58°F (15°C) | 3.0" | 0.7 | 0.0 |
| December | 62°F (17°C) | 40°F (4°C) | 51°F (11°C) | 3.6" | 4.2 | 0.0 |
The year, day by day
The year in Sullivans Island runs from a mild 36°F around January 13 to 91°F at the peak near July 13, and the normal low never reaches freezing on any date in the record.
When the heat sits
Normal highs reach 90°F from June 28 through August 17, covering 51 dates. The broader mild season, normal highs of 70°F or more, runs March 29 to November 12.
This counts calendar dates whose 1991–2020 normal high reaches 90°F. It is a smaller number than the 90°F+ day counts in the monthly table above, which measure how often the threshold was actually crossed in a typical year. A date can average 88°F and still exceed 90°F in half of all years.
No freezing date
Not one calendar date in the 1991–2020 record carries a normal low at or below 32°F. The coldest normal low of the year is 36°F around January 13.
The widest day
January 3 carries the biggest normal gap between afternoon and dawn, 23°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Sullivans Island.
Where Sullivans Island Stands Nationally
The normal water year runs well above the national norm at roughly 52 inches.
Days and nights track unusually close together; the widest normal swing, about 23°F, is narrower than most stations record.
Sullivans Island earns 2 nationally notable standings (outer quintiles) against 6,860 NOAA 1991–2020 normals stations; only those extremes render.
Monthly Precipitation
Average monthly rainfall
Sullivans Island spreads its precipitation across the year
Neither half of the year dominates here: June through August take 35% of the annual total and December through February 21%, with neither reaching the 35% that would mark a distinct wet season. Sullivans Island has no dry season to plan around, though it does carry a 34.2°F seasonal spread.
The gap between the wettest and driest month still matters: August averages 6.7" and November 3.0". The three wettest months together take 35% of the year, against the 25% a perfectly flat distribution would give them.
Shares are computed from this station's own 1991-2020 monthly precipitation normals. "Spread across the year" means neither the June-August nor the December-February share reaches 35%; it describes an average year, not the variability of any single one.
Frost Dates & Growing Season
First Fall Freeze
November 30
50% probability date
Last Spring Freeze
March 13
50% probability date
Growing Season
262 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
2,051
Higher = more heating needed
Cooling Degree Days
2,279
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside SC closest to Sullivans Island on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (66°F here).
- Athens, TX 66°F · 0.0°F off
- Blanco, TX 66°F · 0.0°F off
- Brewton, AL 66°F · 0.0°F off
- Bunkerville, NV 66°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (51.6" here), excluding temperature-peer places.
- Bardstown, KY 51.6" · 0.0" off
- Stamford, CT 51.6" · 0.0" off
- Cape Neddick, ME 51.6" · 0.0" off
- Blytheville, AR 51.6" · 0.0" off
Data-derived climate profile
How Sullivans Island's climate pattern fits together
mixed demand · wet · mid swing
Water is prominent even though neither heating nor cooling wholly defines the record. Sullivans Island averages 51.6 inches of precipitation a year. Snowfall is not added to the interpretation because its annual value is missing. The monthly table supplies the seasonal distribution hidden by that annual total.
July and January mark the typical warm and cold ends of the calendar in Sullivans Island's middle-range seasonal profile. The measured spread is 34.2°F. The annual average is 66°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Heating and cooling both register in Sullivans Island's normal, at 2,051 and 2,279 degree days respectively. Neither total exceeds the other by more than two to one, so the record is better read as a mixed-demand calendar than as heating-led or cooling-led.
The frost-free window extends for about 262 days. That is a long calendar measure, but it is not a forecast and does not combine heat, rainfall, soil, or local elevation into a planting recommendation.
These labels group NOAA 1991-2020 normals from Sullivans Island's primary station, where heating and cooling demand are close enough that neither season sets the character on its own. On a balanced station like Sullivans Island, the bands are descriptive ranges rather than an official NOAA classification or a forecast.
Questions about Sullivans Island's climate
How much rain does Sullivans Island get? ▼
How many days above 90°F does Sullivans Island get? ▼
How much energy does heating and cooling require in Sullivans Island? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Sullivans Island's primary station: SULLIVANS IS (USC00388405). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The conservative exact name-and-state crosswalk finds no Census place match, so PlainClimate treats this as a station-mapped location and does not claim it is a municipality. No exact Gazetteer row for Sullivans Island; facility counts that depend on place identity are therefore an upper bound, not a municipal census.
On this page every temperature, precipitation, and derived score for Sullivans Island comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.