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South Carolina · Mosquito Season Guide

Is it mosquito season in South Carolina?

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II. South Carolina Mosquito Season Month by month

South Carolina divides cleanly between its coastal plain and Upstate Piedmont, and those regions run meaningfully different mosquito seasons. The Low Country — from Charleston south to Beaufort and Hilton Head — is one of the most active stretches of East Coast mosquito habitat, sustained by tidal marshes, river floodplains, and subtropical summer temperatures.

Low Country / Coast
Charleston · Myrtle Beach · Hilton Head
Midlands & Upstate
Columbia · Greenville · Spartanburg
Very Low Low Moderate High Very High taller = more active · color = severity
~60
mosquito species recorded in South Carolina
~260
days of possible activity in Low Country counties
3
disease-vectoring species of concern
46
counties — all with seasonal exposure

The Low Country: the most active zone on the East Coast

Charleston, Beaufort, Colleton, Jasper, and Horry counties sustain some of the densest mosquito populations on the Atlantic seaboard. Tidal salt marshes breed Ochlerotatus sollicitans (salt marsh mosquito) in enormous numbers — coastal residents often describe summer evenings as essentially unbearable without protection. Activity begins in March and stays meaningful through November.

The Midlands: Columbia and the Sandhills

Columbia and the central Midlands follow a standard Deep South pattern: season builds April–May, peaks through summer, and fades in October. The Broad, Saluda, and Congaree river systems create extensive floodwater habitat that drives population surges after spring and summer storms.

The Upstate Piedmont: shorter but real

Greenville, Spartanburg, and the Upstate Piedmont experience a shorter season, typically May through September, with peak intensity in July–August. Cooler temperatures and less standing water limit the extreme density seen on the coast, but Asian tiger mosquito populations are well established throughout the region.

III. South Carolina's Three Species to Know
Culex quinquefasciatus macro photograph
Culex quinquefasciatus
Southern House Mosquito

The primary West Nile Virus vector in South Carolina. A dusk-to-dawn biter breeding in stagnant water statewide. Dominant in Columbia and urban coastal areas. Present from late spring through fall across all 46 counties.

Aedes albopictus — Asian tiger mosquito macro photograph
Aedes albopictus
Asian Tiger Mosquito

Established statewide and one of the most complained-about species in South Carolina suburbs. Bites aggressively during the day — making standard dusk/dawn-only protection insufficient for anyone spending time outdoors during peak season.

Salt marsh mosquito photograph
Ochlerotatus sollicitans
Salt Marsh Mosquito

The defining coastal species of the South Carolina Low Country. Breeds in salt marsh habitat in enormous numbers and disperses miles inland on wind. Coastal residents near tidal areas in Charleston, Beaufort, and Horry counties experience the highest exposure from this species.

IV. South Carolina Cities at a Glance
CityPeak SeasonOff-SeasonNotes
Charleston Mar – Nov Low Dec–Feb Tidal salt marshes create intense coastal pressure; one of the most active East Coast metros Check live
Myrtle Beach Mar – Nov Low Dec–Feb Grand Strand salt marsh and freshwater impoundments; tourist season overlaps with peak mosquito season Check live
Hilton Head Mar – Nov Low Dec–Feb Sea island marshes; resort areas apply significant control but activity remains high Check live
Columbia Apr – Oct Off Nov–Mar Congaree River floodplain drives surges; Shandon and Forest Acres neighborhoods see tiger mosquito pressure Check live
Greenville May – Sep Off Oct–Apr Piedmont foothill season; Reedy River corridor; shorter window but tiger mosquito well established Check live
More State Guides
Florida Year-round activity in the south — 80+ species including invasive Ae. aegypti and the Asian tiger mosquito across all 67 counties Texas ~85 species across four climate zones — Gulf Coast active March through November, with year-round pressure in the Rio Grande Valley California Central Valley is the #1 West Nile corridor in the US — invasive Ae. aegypti and Ae. albopictus now established in 20+ counties Georgia Atlanta metro leads the Southeast in Asian tiger mosquito density — active statewide March through November New York Ground zero for West Nile in the US (1999 Queens outbreak) — NYC metro and Long Island see the highest Northeast seasonal pressure Illinois Home of the 2002 Cook County West Nile outbreak — the deadliest urban WNV event in US history — peak season June through September Ohio Lake Erie to the Ohio River — WNV active in Franklin and Cuyahoga counties, with floodwater species surging after summer storms Pennsylvania Philadelphia WNV corridor meets rural EEE risk in western PA — the densest human population in the mid-Atlantic mosquito belt Michigan Site of the 2019 EEE outbreak — the deadliest in decades — 10 human cases and 6 deaths concentrated in SW Michigan Great Lakes wetlands New Jersey Oldest organized county mosquito control in the US (1914) — Pine Barrens EEE corridor and fierce salt marsh Shore species Virginia Tidewater season runs April–October — the longest mid-Atlantic window — with the Great Dismal Swamp as an active EEE hotspot North Carolina The coastal plain runs one of the longest seasons in the Southeast — NC leads the nation in La Crosse encephalitis cases from the Appalachian foothills Maryland Chesapeake Bay watershed creates extraordinary mosquito habitat — tidal marshes, Eastern Shore wetlands, and the DC-Baltimore corridor combine for dense seasonal pressure Tennessee Memphis and the Mississippi River corridor historically record the highest WNV case counts in the mid-South — Ae. albopictus has colonized all 95 counties Indiana Indiana sits at the crossroads of the Great Lakes EEE belt — Lake Michigan wetlands in the north and the Wabash River floodplain drive intense seasonal pressure Louisiana The Gulf Coast's most intense pressure — coastal marshes and summer rains keep Cx. quinquefasciatus and Ae. aegypti active from March through November Alabama Mobile Bay to the Tennessee Valley — Ae. albopictus has reached all 67 counties and peak WNV season runs June through September Minnesota 10,000 lakes means 10,000 breeding sites — the Northwoods sees intense but short July–August peaks, while the Twin Cities face a longer June–September window Wisconsin Great Lakes wetlands and the Mississippi River backwaters drive strong WNV pressure in the Milwaukee corridor — peak season July through August Missouri At the confluence of the Missouri and Mississippi rivers — St. Louis historically ranks among the highest WNV cities in the US — season May through October Arkansas Delta rice-field flooding and the Arkansas River bottomlands create some of the highest rural mosquito pressure in the mid-South — active April through October Washington Western WA stays mild and damp year-round; the Yakima Valley and Columbia Basin face the highest WNV risk in the Pacific Northwest — peak July through September Arizona Monsoon season (July–September) drives sudden mosquito explosions across the Valley of the Sun — WNV detected annually Colorado Front Range WNV corridor stretches Denver to Fort Collins — eastern plains carry the state's highest risk Connecticut Connecticut River valley WNV pressure meets EEE risk in inland freshwater wetlands — active May through October Delaware Chesapeake and Delaware Bay marshes create outsized pressure for the nation's second-smallest state Hawaii Year-round activity at sea level — no native species, but Ae. aegypti and tiger mosquitoes established statewide Idaho Snake River Plain irrigation districts fuel summer WNV pressure — season June through September Iowa Mississippi River corridor and prairie wetlands drive intense June–September pressure — WNV active statewide Kansas Great Plains WNV corridor — Wichita and Kansas City see peak pressure July–August; floodwater species surge after storms Kentucky Ohio River corridor and Kentucky Lake wetlands sustain a long April–October season across all 120 counties Maine Short but intense July–August season — EEE detected in some years in the southern coastal plain Massachusetts EEE fatality rate exceeds 30% — the Plymouth County swamp complex is the active epicenter — season May through October Mississippi Gulf Coast near-year-round pressure meets Delta rice-field flooding for one of the South's most intense mosquito environments Montana Yellowstone and Missouri River corridors drive a compressed June–August season — WNV detected most years in eastern MT Nebraska Platte River valley and eastern Nebraska are among the Great Plains' most active WNV zones — peak July–August Nevada Las Vegas monsoon season drives July–September activity; Reno irrigation districts fuel a parallel northern peak New Hampshire EEE detected most years — the southern lakes and coastal plain are in the active Northeast EEE corridor New Mexico Monsoon season (July–September) creates sudden breeding habitat; WNV circulates in the Rio Grande valley annually North Dakota Red River Valley flooding produces some of the Great Plains' most extreme floodwater mosquito events — peak June–August Oklahoma One of the South-Central's most intense seasons — the Arkansas and Red River corridors sustain populations April through October Oregon Eastern Oregon Columbia Basin is the state's WNV hotspot; western Oregon runs a mild coastal season June through September Rhode Island New England's densest coastal pressure — Narragansett Bay salt marshes and WNV active in all five counties South Dakota Missouri River and James River valleys drive summer WNV activity — eastern SD sees the most intense pressure Utah Salt Lake Valley WNV corridor and irrigation districts sustain a July–September peak — drier areas see limited activity Vermont Champlain Valley runs Vermont's longest season — EEE detected in the Lake Champlain lowlands in some years West Virginia Kanawha and Ohio River valleys sustain a May–October season — Ae. albopictus now established statewide Wyoming The shortest meaningful season of any contiguous US state — North Platte valley WNV window is just 6–8 weeks
West Nile, dengue, and EEE: US disease risk by region → Asian tiger mosquitoes: why you're getting bitten during the day → Eliminating standing water: the highest-leverage yard move →