| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 38°F | 64°F | 50°F | 2.9" |
| February | 39°F | 66°F | 51°F | 3.7" |
| March | 45°F | 72°F | 58°F | 3.1" |
| April | 53°F | 80°F | 66°F | 3.4" |
| May | 62°F | 85°F | 73°F | 3.4" |
| June | 70°F | 91°F | 79°F | 6.6" |
| July | 73°F | 92°F | 82°F | 6.5" |
| August | 73°F | 91°F | 81°F | 8.0" |
| September | 68°F | 87°F | 76°F | 5.9" |
| October | 56°F | 80°F | 67°F | 5.6" |
| November | 45°F | 72°F | 57°F | 2.9" |
| December | 42°F | 67°F | 53°F | 3.7" |
| Index | Sullivan's Island | South Carolina | National |
| Air quality index | 38 | 37 | 42 |
| Pollution index | 783,589 | 3,620,438 | 2,726,193 |
| Measurement | Total |
| Days measured | 355 |
| Days with good air quality | 299 |
| Days with moderate air quality | 55 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.003% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Isle of Palms, SC | 4,371 | 38 | 24.0% |
| North Charleston, SC | 113,880 | 38 | 24.0% |
| Charleston, SC | 137,041 | 38 | 24.0% |
| James Island, SC | 12,157 | 38 | 24.0% |
| Folly Beach, SC | 2,664 | 38 | 24.0% |
| Sullivan's Island, SC | 2,177 | 38 | 24.0% |
| City | Population | Air Quality Index | National Avg. |
| Prairie Creek, AR | 2,176 | 44 | 12.0% |
| Mokuleia, HI | 2,176 | 30 | 40.0% |
| Cedar Point, NC | 2,176 | 37 | 26.0% |
| Fannett, TX | 2,176 | 45 | 10.0% |
| Leslie, MI | 2,178 | 36 | 28.0% |
| Sullivan's Island, SC | 2,177 | 38 | 24.0% |
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