Last updated: April 2026 • Sources: Virginia Department of Health (VDH), CDC, Fairfax County Health Department, Virginia Beach Public Works Mosquito Control Bureau, Vector Disease Control International.
Table of Contents
Introduction: When Mosquito Peaks in Virginia
Mosquito season in Virginia is not just an annual inconvenience. It’s a legitimate public health window — one that opens earlier every year and, in some regions, barely closes.
If you’ve spent any time outdoors in Richmond, Fairfax, Virginia Beach, or the Shenandoah Valley in summer, you already know the feeling. The moment temperatures climb and rain arrives, mosquito populations can surge fast. And the health risks they carry aren’t trivial.
This guide covers when mosquito season actually starts and ends in Virginia, which months carry the highest risk, what diseases are circulating in 2026, and practical steps you can take based on data from the Virginia Department of Health (VDH) and the CDC.
When Does Mosquito Season Start and End in Virginia?
The short answer: late March to early April through October or November, depending on where you live in the state.
Mosquito activity is driven primarily by temperature. The general threshold is 50°F (10°C) — once daily temperatures stay consistently above that level, eggs begin hatching and dormant adults become active again.
Virginia’s geography makes this complicated. The Tidewater region around Norfolk and Virginia Beach warms earlier in spring than the higher elevations of Southwest Virginia. That means coastal residents can see their first bites weeks before someone living in the Blue Ridge Foothills.
Monthly Mosquito Activity Calendar for Virginia (2026)
Activity levels are generalizations based on historic climate patterns and VDH surveillance data. Actual conditions vary by region and year.
| Month | Activity Level | Risk Notes |
| January – February | Negligible | Adults dormant; Aedes eggs overwintering in soil |
| March | Very Low | Coastal VA may see early emergence on warm days |
| April | Low to Moderate | Season starts in Tidewater; inland areas still quiet |
| May | Moderate | Statewide emergence; post-rain breeding surges |
| June | High | Rapid population growth; first disease detections |
| July | Very High — Peak | Hottest breeding period; WNV transmission risk elevated |
| August | Very High — Peak | Continued peak; EEE risk window active in wetland areas |
| September | High | Late-season surge; WNV positive pools still reported |
| October | Moderate | Declining but active above 50°F; tropical remnants can spike |
| November | Low to Negligible | Activity ends after first frost; coastal areas linger |
| December | Negligible | Season effectively closed |
Virginia Mosquito Activity by Month (2026)
Estimated activity index 0–10 based on VDH surveillance data and regional climate patterns
Peak Mosquito Months in Virginia: June, July, and August
July and August are the undisputed peak of mosquito season in Virginia. Daily highs in the upper 80s and 90s, combined with high humidity, can compress the mosquito breeding cycle to as little as five to seven days in Northern Virginia according to vector control monitoring data.
June gets overlooked but shouldn’t. Populations build fast once summer rains begin. By the time you notice mosquitoes are “bad,” the breeding population is already established. That’s the catch — the visible adults you’re swatting are the lagging indicator.
Afternoon thunderstorms, which are extremely common across Central and Northern Virginia from June through August, create repeated pulses of standing water. Each new pulse triggers a fresh wave of egg-laying. A single female mosquito needs just one inch of standing water to lay batches of 100 to 200 eggs, and those eggs hatch into larvae within 24 to 48 hours under warm conditions.
Mosquito-Borne Diseases in Virginia: 2026 Risk Overview
Virginia is not a state where mosquito-borne disease risk can be dismissed. Several viruses circulate here annually, and surveillance data from VDH and county health departments shows ongoing transmission during peak months.
1. West Nile Virus (WNV): The Most Common Threat
West Nile Virus is, by a wide margin, the most frequently reported mosquito-borne disease in Virginia. According to the Virginia Department of Health, WNV is transmitted primarily by Culex mosquitoes, which peak in late summer and bite most aggressively at dusk and night.
The VDH notes that cases generally occur during the summer and early fall. Data from Virginia’s Fairfax Health District shows 30 WNV cases were reported in the district over the ten-year period from 2015 to 2024 — an average of about three cases per year — with 67% of those involving neuroinvasive disease. The district reported its first WNV-positive mosquito pool of the 2025 season in June.
In September 2025, the Richmond and Henrico Health Districts publicly alerted residents after at least 50 percent of mosquito trap sites in Henrico County tested positive for WNV within a two-week window. Nationally, 2025 WNV case counts increased approximately 42% compared to 2024, according to data compiled from CDC surveillance.
Most people infected — roughly 70 to 80 percent — have no symptoms. But about 1 in 5 develop fever and flu-like illness, and approximately 1 in 150 develop neuroinvasive disease such as encephalitis or meningitis. Older adults face a substantially higher risk of severe outcomes.
West Nile Virus: U.S. Reported Cases Trend (2018–2025)
National annual case totals — 2025 data reflects a notable 42% year-over-year increase per CDC surveillance
2. Eastern Equine Encephalitis (EEE): Rare but Serious
EEE is far less common than WNV in Virginia, but it carries a mortality rate of approximately 33% in severe cases — making it one of the deadliest mosquito-borne viruses in the United States. The Virginia Beach public health department describes it as “one of the most severe mosquito-transmitted diseases” in the country.
The primary vector for EEE among birds is Culiseta melanura, which breeds in freshwater swamps. Bridge vectors — including some Aedes and Coquillettidia species — are responsible for human and horse transmission. Residents living near wetlands, tidal marshes, or forested swamp areas in Virginia carry elevated risk during August and September.
3. La Crosse Encephalitis (LACV) and St. Louis Encephalitis (SLE)
Both viruses circulate in Virginia at low levels. La Crosse encephalitis is transmitted by the treehole mosquito and primarily affects children under 16. St. Louis Encephalitis, vectored by Culex species, affects adults over 50 most severely. Nationally, 2025 data showed significant increases in both — with SLE cases up approximately 200% year-over-year and LACV up over 200%, though from a small base.
Asian Tiger Mosquito (Aedes albopictus): An Expanding Concern
Virginia Beach’s public health office confirms that Aedes albopictus — the Asian tiger mosquito — is present across Virginia and is the more common of the two primary Aedes species in the region. It’s a capable vector for Zika, dengue, and chikungunya.
Unlike Culex mosquitoes, the Asian tiger mosquito bites aggressively during daylight hours. It breeds in tiny containers — bottle caps, clogged gutters, flower pot saucers. Urbanization creates ideal habitat. As climate patterns shift and milder winters become more frequent, its established range continues to expand northward across Virginia.
Virginia Mosquito Disease Risk Summary
| Disease | Primary Vector | Peak Risk Period | Severity |
| West Nile Virus | Culex pipiens/quinquefasciatus | July – September | Moderate–Severe |
| Eastern Equine Encephalitis | Culiseta melanura (bridge vectors) | August – September | Severe (33% fatality) |
| La Crosse Encephalitis | Aedes triseriatus | July – August | Moderate (children) |
| St. Louis Encephalitis | Culex species | July – September | Moderate–Severe |
| Zika / Dengue (travel-assoc.) | Aedes albopictus/aegypti | June – October | Varies |
Note: Zika and dengue risk in Virginia is currently considered travel-associated. Local transmission from Virginia-based mosquitoes is not currently documented at scale by VDH.
Virginia Mosquito-Borne Disease Risk by Month
Risk level per disease across the calendar year — hover cells for details
Climate Trends and What They Mean for Virginia’s Mosquito Season
Warmer winters, earlier springs, and wetter late summers are changing the seasonal math for mosquitoes in Virginia. Climate variability — particularly mild, soggy winters — gives overwintering mosquitoes an easier transition into spring, which can translate to larger early-season populations.
The Asian tiger mosquito’s overwintering eggs are well-adapted to mild winters. In a year where temperatures don’t drop hard enough for long enough, that dormancy period shortens, and the breeding season on both ends expands.
Research published in peer-reviewed literature suggests that as temperatures rise, the Aedes albopictus range continues to shift poleward. That means parts of Virginia that historically had manageable mosquito pressure could see longer seasons and higher populations in coming decades.
None of this is cause for alarm — it’s a reason for informed preparation. The Virginia Department of Health and local mosquito control bureaus like the one in Virginia Beach already conduct year-round surveillance, larval control, and targeted spraying based on trap data and sentinel chicken monitoring.
High-Risk Zones in Virginia: Where Mosquito Pressure Is Greatest
Virginia’s geography creates distinct mosquito risk zones. They’re not evenly distributed across the state.
| Region | Mosquito Pressure | Key Risk Factors |
| Tidewater / Hampton Roads | Very High | Tidal marshes, warm winters, saltmarsh species |
| Northern Virginia (DC suburbs) | High | Dense development, stream valleys, summer storms |
| Richmond Metro | High | James River corridor, urban standing water, WNV history |
| Eastern Shore | High | Wetlands, agricultural drainage ditches, isolated communities |
| Piedmont (Charlottesville area) | Moderate–High | Seasonal flooding, wooded lots, summer humidity |
| Shenandoah Valley | Moderate | Lower humidity; cooler nights limit late-season activity |
| Southwest Virginia / Highlands | Low–Moderate | Elevation, cooler temps; shorter active season |
Mosquito Pressure by Virginia Region
Composite risk score (0–10) based on climate, geography, species presence, and historical disease surveillance
Virginia Mosquito Prevention: What Actually Works in 2026
Surveillance and professional control programs do a lot of the heavy lifting at the community level. But individual protection remains important, especially during peak months.
i) EPA-Registered Repellents
The CDC recommends repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone. These are registered with the EPA and have demonstrated effectiveness when applied as directed. DEET-based repellents at concentrations of 20–30% provide several hours of protection for most adults.
ii) Eliminate Standing Water Around Your Property
This is, consistently, the single most effective individual-level action. A female mosquito needs as little as one inch of standing water. Target: flower pot saucers, gutters, bird baths, tarps, kids’ toys, any container that collects water. Refresh bird baths at least every few days during peak season.
iii) Timing Outdoor Activities
Culex mosquitoes — the primary WNV vectors — are most active at dusk and through the night. Scheduling outdoor activities earlier in the day reduces exposure to this species. The Asian tiger mosquito, however, bites during daylight, so daytime protection matters too, especially in wooded suburban areas.
iv) Protect Your Home
Keep window and door screens in good repair. Use air conditioning where possible during peak months. Virginia Beach’s public works department offers one-time mosquito inspections and treatments to residents from May to October — many Virginia counties offer similar programs. Check with your local health district.
Community Surveillance Matters
Virginia Beach maintains a network of sentinel chickens across the city that are tested weekly for WNV and EEE antibodies. This early-warning system informs targeted spraying decisions. Similar programs run in other Virginia localities. These systems work — but they depend on continued public investment and attention.
| Prevention Method | Targets | Effectiveness |
| EPA-registered repellent (DEET/picaridin) | Adult mosquitoes | High |
| Eliminate standing water | Breeding interruption | Very High |
| Larvicide treatment (professional/DIY) | Larvae before emergence | High |
| Window/door screens | Indoor entry prevention | Moderate–High |
| Protective clothing (long sleeves/pants) | Bite reduction at dusk/dawn | Moderate |
| Avoid peak activity hours (dusk–midnight) | Culex exposure reduction | Moderate |
| Community barrier spray programs | Area-wide population reduction | Moderate (targeted) |
Mosquito Prevention Methods: Relative Effectiveness
Score reflects reduction in mosquito exposure or disease transmission risk — CDC and VDH guidance
Who Is Most Vulnerable to Mosquito-Borne Illness in Virginia?
Not everyone faces the same risk from a mosquito bite. Age and health status are the most consistent factors across major Virginia mosquito diseases.
- Adults over 50 face the highest risk of severe neuroinvasive disease from WNV and SLE
- Children under 16 are most vulnerable to severe outcomes from La Crosse encephalitis
- People who are immunocompromised face elevated risk from any mosquito-borne virus
- Pregnant women should take extra precautions, particularly during Zika surveillance periods
- Outdoor workers — landscapers, construction workers, agricultural workers — have higher exposure during peak hours
Most WNV infections, again, produce no symptoms or only mild illness. But the 70 to 80 percent who don’t get sick shouldn’t create a false impression that the risk is negligible for everyone — especially older adults.
Virginia Mosquito Health Resources
The following agencies provide up-to-date information and surveillance data for Virginia residents:
- Virginia Department of Health (VDH) — vdh.virginia.gov/mosquitoes — Disease data, prevention tips, local health district contacts
- CDC West Nile Virus Surveillance — cdc.gov/west-nile-virus — National and state-level case maps, updated in summer and fall
- Virginia Beach Public Works Mosquito Control Bureau — (757) 385-1470 — Residential inspections and treatments
- Fairfax County Health Department — Publishes mosquito trap results and WNV pool testing data each summer
The Bottom Line on Virginia’s 2026 Mosquito Season
Mosquito season in Virginia is a real, data-trackable public health event — not background noise. The peak runs from late June through August, with meaningful risk extending into September, especially for West Nile Virus.
The state has solid surveillance infrastructure. VDH and local mosquito control bureaus are actively monitoring, testing, and responding. But individual action matters during these months, particularly for older adults and people living near wetland areas.
Use repellent. Drain standing water. Check your screens. Know the risk factors for your zip code. And if symptoms consistent with mosquito-borne illness appear — fever, severe headache, stiff neck, disorientation — contact your healthcare provider and mention potential mosquito exposure.
It doesn’t take alarm to take this seriously. Just a little awareness and a few habits, applied during the right months.
