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II · Season Timing

Typical season — Nashville

West Tennessee starts earlier and runs hotter — the Memphis corridor is Tennessee's primary WNV zone

West Tennessee

Memphis · Jackson · WNV corridor

Middle & East Tennessee

Nashville · Knoxville · Chattanooga

Minimal Low Moderate High Peak taller = more active · color = severity

Choose a city

55+

mosquito species recorded in Tennessee

Mar–Oct

typical active season statewide

June–Aug

peak pressure months

WNV

primary disease risk — Memphis corridor

IV · Key Species

Culex quinquefasciatus

⚠ WNV Vector — Primary Risk

The southern house mosquito is Tennessee's dominant West Nile virus vector and the primary driver of WNV transmission in Memphis and the surrounding delta region. It breeds prolifically in warm, organically enriched water — storm drain pools, drainage ditches, and stagnant ponds. Active from dusk through dawn, peak abundance in July and August. Shelby County (Memphis) consistently records the highest statewide WNV case counts.

Aedes albopictus

Asian Tiger Mosquito

The Asian tiger mosquito has established itself in all 95 Tennessee counties — one of the most complete state infestations in the US. It is an aggressive daytime biter, most active in shaded suburban and woodland areas from mid-morning through late afternoon. Breeds in any small container holding water: tire swings, bird baths, pot saucers, clogged gutters. Active from late April through October across most of the state.

Aedes vexans

Inland Floodwater Mosquito

The inland floodwater mosquito thrives in Tennessee's river systems — the Cumberland, Tennessee, and Mississippi watersheds all generate large seasonal populations. Dormant eggs in floodplain soils hatch en masse after significant rainfall or river flooding events. Western Tennessee's flat, low-lying terrain is particularly productive; populations can surge from minimal to overwhelming in fewer than five days following a storm system moving up from the Gulf.

V · Tennessee Mosquito Context

Memphis and the Mississippi River WNV corridor

Memphis occupies one of the highest-risk West Nile virus corridors in the United States. The Mississippi River's oxbow lakes, backwater sloughs, and low-lying floodplain create vast warm-water breeding habitat for Culex quinquefasciatus — the southern house mosquito and the primary WNV vector in the region. Shelby County regularly leads Tennessee in confirmed human WNV cases, with some years seeing case totals that exceed the combined count of the rest of the state. The Mississippi Delta mosquito season is also the longest in Tennessee, often running from late February through early November in warm years. Check TDOH West Nile surveillance →

Aedes albopictus in all 95 counties

Tennessee is one of a handful of US states where Aedes albopictus has been confirmed in every single county. The species arrived in the state through the used-tire trade in the late 1980s and has since colonized every habitat from urban Memphis and Nashville to rural mountain communities in Unicoi and Carter counties along the North Carolina border. Its aggressive daytime biting behavior sets it apart from the nocturnal Culex species — residents who repel themselves only at dusk still get bitten through the day. Any container that holds water for more than a week is a potential breeding site.

East Tennessee — Smoky Mountains and the Tennessee River valley

The Great Smoky Mountains and the Ridge and Valley terrain of East Tennessee create a cooler, slightly shorter season than the western part of the state — Knoxville and Chattanooga typically see their first significant pressure in April rather than March, and the season wraps in September. The Tennessee River system and its tributary valleys remain highly productive breeding habitat through the summer months. Chattanooga's position in a river valley between ridgelines means calm, humid summer nights with sustained Culex activity. Great Smoky Mountains National Park receives roughly 13 million visitors per year during the peak mosquito months of June through August — outdoor recreation in wooded areas carries real Ae. albopictus exposure during daylight hours.

VI · City-by-City Breakdown

City	Season	Off-season	Notes	Live data
Nashville	Mar – Oct	Off Nov–Feb	Davidson County; Cumberland River corridor and Percy Priest Lake watershed amplify breeding habitat; Cx. quinquefasciatus and Ae. albopictus both abundant; urban heat island effect sustains pressure through October; WNV detected in Davidson County trap pools most summers; one of the longest seasons in Middle Tennessee	Check live
Memphis	Feb – Nov	Off Dec–Jan	Shelby County leads Tennessee in annual WNV case counts; Mississippi River oxbow lakes and backwater sloughs provide massive Cx. quinquefasciatus habitat; West Memphis metro is functionally continuous with the Arkansas Delta mosquito zone; Ae. vexans flood pulses regularly follow spring and summer thunderstorms; longest season in the state	Check live
Knoxville	Apr – Sep	Off Oct–Mar	Knox County; Tennessee River and Fort Loudoun Lake; elevation moderates early-season pressure compared to western TN; Ae. albopictus well established throughout Knoxville suburbs; proximity to Great Smoky Mountains — hikers and campers face daytime Ae. albopictus exposure in wooded areas; WNV detected in Knox County; peak July–August	Check live
Chattanooga	Apr – Oct	Off Nov–Mar	Hamilton County; Tennessee River valley with ridge and valley terrain that traps humid air — sustained nocturnal Culex conditions through summer; Chickamauga Lake backwaters productive breeding habitat; Ae. albopictus active in wooded neighborhoods through October; WNV present in local surveillance; Lookout Mountain and Signal Mountain elevations see slightly shorter season	Check live
Clarksville	Mar – Oct	Off Nov–Feb	Montgomery County; Cumberland River watershed; Fort Campbell military installation spans the TN-KY border and maintains its own vector surveillance program; Ae. albopictus and Cx. quinquefasciatus both present; river bottom terrain with Red River tributary creating additional floodwater habitat; season comparable to Nashville with earlier spring onset	Check live
Murfreesboro	Mar – Oct	Off Nov–Feb	Rutherford County; Stones River watershed; rapidly growing suburb south of Nashville with significant container breeding pressure as new residential development creates standing water in construction areas; Ae. albopictus and Cx. quinquefasciatus both common; season mirrors Nashville; Stones River floodplain terrain adjacent to suburban neighborhoods	Check live
Jackson	Mar – Oct	Off Nov–Feb	Madison County; West Tennessee — climatically closer to Memphis than Nashville; South Fork Forked Deer River watershed with extensive floodplain wetlands; Ae. vexans flood pulses common after heavy rainfall; Cx. quinquefasciatus active through summer; Ae. albopictus well established in residential areas; WNV detected in West Tennessee corridor including Madison County	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 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 South Carolina Low Country marshes produce some of the Southeast's densest Anopheles and Culex populations — season runs March through November 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 →