Hurricanes and Tornadoes That Hit Johns Island, SC

The nearest NOAA station with 1991–2020 climate normals is Charleston City, SC, 10 miles northeast of Johns Island at 10 feet. July is the warmest, with an average high of 88°F and low of 77°F; January is the coolest, at 58°F and 44°F. August is the wettest at 6.1 inches of precipitation on average and November the driest at 2.3 inches; the year adds up to 44.5 inches over 65 days with at least a tenth of an inch. June to November, the hurricane season months, bring 62% of the year's precipitation (27.8 of 44.5 inches); the other six months are drier. September has brought the most of the 109 tropical systems that passed within 75 miles (34); a normal September there has highs of 83°F and 5.3 inches of precipitation. Highs reach 90°F on about 25 days a year, almost all from May to September. Lows fall below freezing on about 6 nights a year. That 44.5 inches is more than at 9 of the 78 South Carolina stations used on this site (12%). Wadmalaw Island, 7 miles southwest, has its own station (Edisto Is Middleton Plantation, SC): 52.1 inches a year, 7.6 more than here, and a July average high of 90°F against 88°F.

Water temperature at the NOAA tide station Charleston, SC, 10 miles northeast, averaged 86°F in July and 54°F in January over 2021–2025. It averaged 80°F or warmer from June to September. Sea level at the Charleston tide gauge, 10 miles from Johns Island, has risen 1.38 ± 0.04 inches per decade from 1901 to 2025, NOAA's linear trend; at that pace it is 13.8 inches in a hundred years. That is faster than at 82 of the 144 U.S. gauges with a NOAA trend.

Since 1996, the National Weather Service has logged 394 flood, rain, thunderstorm wind and lightning events that began within 10 miles of Johns Island: 212 thunderstorm wind reports, 154 flash floods, 21 lightning strikes, 4 floods and 3 heavy rain events. They killed 0 people and injured 2, and the NWS estimated $11.6 million in property and crop damage. The strongest thunderstorm gust on record here was 96 mph, on April 5, 2022. August has had the most flash floods, 58 of 154. Of the 241 South Carolina cities on this site with a flash flood on record, 231 have had fewer than Johns Island.

Flood insurance policyholders in Johns Island's ZIP code 29455 have filed 1,029 claims with the National Flood Insurance Program since 1979, and were paid $4.2 million for buildings and contents, in the dollars of each year. The most came from Hurricane Hugo in 1989: 418 claims (41% of all) and $292,000, then October severe storms in 2015 with 165 and Hurricane Irma in 2017 with 148. 91% of the claims carry the name of a storm or flood event; the rest have no event name. Of the 110 South Carolina cities on this site with 10 or more claims, 98 have fewer than Johns Island.