Weather

Marsh by South Channel at Low Tide

NPS Photo - Davey Allen

Hot, Wet, & Stormy

The Lowcountry (coastal region of Georgia & South Carolina) in the 17^th and 18th centuries was a wild, dangerous subtropical wilderness for European colonists. The citizens of Charleston (founded 1670) and Savannah (founded 1733) had to contend with a harsh environment which posed continual problems of heat, humidity, and hurricanes. Lowcountry winters are short (December to February typically), and springs/summers are quite long. Breezy conditions near coastal waters have a moderating effect on temperatures, so heat and cold tend to be less extreme compared to inland regions. The subtropical climate of the Lowcountry region also greatly exacerbated the spread among colonists of such diseases as yellow fever, malaria, smallpox, and typhus. The average annual rainfall ranges from 30 to 50 inches in the island regions. A large high pressure cell, called the Bermuda high, affects the Southeast in summer months. The Bermuda high diverts large continental storms away from the Lowcountry. Summer rains in the Lowcountry tend to result from local convection storms as a result. These convection storms don’t always produce rainfall, however; periods of summer drought are not uncommon. When summers draw to a close, so too does the Bermuda high. This exposes the Lowcountry region to large, frontal storm systems which can produce tropical storms and hurricanes.

 

A mudflat at low tide on Cockspur Island

NPS Photo - Davey Allen

In the colonial days, permanent residents took their chances and chose to remain after getting used to the climate conditions, but newcomers to the region did not have the same tolerance. New inhabitants, black or white, who did not have the ability to seek a home in a more welcoming climate were constantly battered by strong storms. These storms became a source of great concern for France and Britain, whose navies were exposed to much risk in American coastal waters. In Savannah, these concerns were exemplified in the troubles French Admiral d’Estaing’s fleet encountered after the Battle of Savannah in October 1779. The French fleet got caught up in a hurricane which sunk some ships and made others vulnerable enough to be seized by the British. The very next year, in 1780, a staggering eight hurricanes threatened the Atlantic and Gulf coasts and produced one of the deadliest years for hurricanes on record. To this day, these hurricanes are particularly dangerous to barrier islands and coastal marshlands because of the virulent winds and enormous storm surges which characterize them. Tidal phenomena are predictable, but the interaction between tidal action and meteorological events can produce extreme and unpredictable results. For example, in areas where salt marsh occurs further inland of barrier islands, storms that breach the islands’ dunes can deposit sediment across a wide swath of marsh. It is critical to the NPS mission that we understand the impact a volatile climate can have on our natural and cultural resources so that we may do our best to minimize negative effects and preserve parks like Fort Pulaski National Monument for years to come.

References

A Guide to a Georgia Barrier Island, Schoettle, Watermarks Publishing (1996)
Lowcountry Hurricanes, Fraser, University of Georgia Press (2006)
Saltmarsh Ecology, Adam, Cambridge University Press (1990)