Last updated: March 2, 2024
Under the Köppen–Geiger climate classification Sullivans Island features a humid subtropical climate (Cfa). Temperatures typically range between 12 °C (53 °F) and 27 °C (81 °F) through the year, but rarely can drop to -5 °C (24 °F) or can rise to as high as 32 °C (90 °F). The average annual precipitation amounts to about 1434 mm (56.4 inches) and receives 138 rainy days on the 1 mm (0.04 inches) threshold annually. Sullivans Island enjoys an average of 3403 hours of sunshine throughout the year, and daylight varies from 10 hours 1 minutes to 14 hours 15 minutes per day.
The warmest months in Sullivans Island are July, August and September, with daily mean temperatures ranging from 26 to 27 °C (79 - 81 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from 12 to 14 °C (53 - 57 °F) throughout the day. On average each year, Sullivans Island experiences 125 days above 25 °C (77.0 °F) and 1 days below 0 °C (32.0 °F).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Maximum | 21°C (70°F) |
21°C (70°F) |
23°C (74°F) |
27°C (81°F) |
31°C (89°F) |
32°C (90°F) |
32°C (89°F) |
31°C (89°F) |
32°C (90°F) |
29°C (85°F) |
26°C (79°F) |
22°C (72°F) |
| Mean maximum | 20°C (68°F) |
20°C (68°F) |
22°C (71°F) |
25°C (76°F) |
28°C (83°F) |
30°C (86°F) |
31°C (87°F) |
31°C (88°F) |
30°C (87°F) |
28°C (82°F) |
24°C (76°F) |
21°C (70°F) |
| Average high | 14°C (58°F) |
16°C (61°F) |
18°C (64°F) |
21°C (70°F) |
25°C (77°F) |
27°C (81°F) |
29°C (84°F) |
29°C (84°F) |
27°C (82°F) |
25°C (76°F) |
19°C (66°F) |
16°C (61°F) |
| Daily mean | 12°C (53°F) |
14°C (57°F) |
15°C (60°F) |
19°C (66°F) |
23°C (74°F) |
26°C (79°F) |
27°C (81°F) |
27°C (81°F) |
26°C (79°F) |
23°C (73°F) |
16°C (62°F) |
13°C (56°F) |
| Average low | 9°C (49°F) |
11°C (53°F) |
13°C (56°F) |
17°C (63°F) |
21°C (71°F) |
24°C (76°F) |
26°C (79°F) |
26°C (79°F) |
24°C (76°F) |
21°C (70°F) |
14°C (57°F) |
11°C (52°F) |
| Mean minimum | 0°C (33°F) |
4°C (39°F) |
5°C (40°F) |
9°C (48°F) |
14°C (58°F) |
20°C (69°F) |
23°C (74°F) |
23°C (75°F) |
20°C (69°F) |
13°C (56°F) |
7°C (44°F) |
4°C (39°F) |
| Minimum | -5°C (24°F) |
2°C (36°F) |
2°C (36°F) |
6°C (42°F) |
12°C (55°F) |
18°C (64°F) |
22°C (72°F) |
23°C (73°F) |
16°C (61°F) |
7°C (46°F) |
3°C (38°F) |
0°C (33°F) |
Compare temperature, precipitation, sunshine, UV index in Sullivans Island, South Carolina, United States with other places around the world.
Sullivans Island usually has the most precipitation in July, August and September, with an average of 17 rainy days and 185 mm (7.3 inches) of precipitation per month. The driest months in Sullivans Island are January, March and May. On average, 70 mm (2.7 inches) of precipitation falls during these months.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Average precipitation mm (inches) | 66 (2.6) | 91 (3.6) | 62 (2.4) | 105 (4.1) | 82 (3.2) | 144 (5.7) | 171 (6.7) | 197 (7.8) | 188 (7.4) | 85 (3.4) | 103 (4.1) | 141 (5.6) |
| Average precipitation days (≥ 1 mm) | 8 | 11 | 7 | 8 | 8 | 17 | 16 | 21 | 14 | 10 | 8 | 10 |
The sunniest months in Sullivans Island are May, June and July, when the sun shines an average of 11 hours 0 minutes a day. Least sunny months in Sullivans Island: January, February and December receive an average of 6 hours 54 minutes of sunshine daily.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean monthly sunshine hours | 190 | 217 | 281 | 312 | 341 | 325 | 345 | 321 | 304 | 293 | 247 | 220 |
| Mean daily daylight hours | 10h 15m | 11h 1m | 12h 0m | 13h 0m | 13h 50m | 14h 15m | 14h 2m | 13h 17m | 12h 19m | 11h 19m | 10h 27m | 10h 1m |
Sullivans Island experiences the highest level of ultraviolet (UV) radiation in May, July and August, when the maximum UV index can reach values of 11 - 12, which corresponds to the Extreme category of sun exposure. January, November and December are in the Moderate / High exposure category. In these months, the maximum values of the UV index do not exceed 6. For more detailed information, check out our hourly Sullivans Island UV Index data.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV Index (month maximum) | 4 | 7 | 9 | 10 | 11 | 11 | 12 | 11 | 9 | 8 | 6 | 4 |
Discover in-depth weather details for every month in Sullivans Island. Click through the links below for comprehensive overviews of temperature trends, precipitation levels, sunshine hours, and solar UV radiation specifics. Whether planning a visit or simply curious about Sullivans Island's climate nuances, these monthly breakdowns provide the information you need for an informed understanding of what to expect throughout the year.
Each link leads to a detailed account of the typical weather conditions for that month, providing both locals and tourists with vital information to plan their daily activities, wardrobe, and travel itineraries accordingly.