Flu season in Southeast: The South leads the nation — flu arrives here first, almost every year
If you want to know where flu season is headed, watch the Southeast. HHS Region 4 is the canary — it goes High in November or December while the rest of the country is still at Very Low or Low. Researchers have debated why for years. The leading explanations converge on two things: Southern school calendars return in late July or early August, weeks before the North, seeding early community spread; and year-round air conditioning keeps people in shared indoor spaces regardless of the season. Whatever the mechanism, the pattern is consistent enough to be predictive.
Current flu activity — HHS Region 4
This data is pulled live from the Delphi CMU Epidata API, which mirrors CDC FluView ILINet data for HHS Region 4. It reflects the most recent week available — typically data through the prior Saturday, published by the CDC the following Thursday.
States in HHS Region 4
HHS Region 4 covers Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, and Tennessee. These states are grouped together by the Department of Health and Human Services for federal health program administration, and the CDC uses the same regional boundaries for flu surveillance reporting. ILI activity data is aggregated across all ILINet providers in the region, so the number reflects the regional average — individual states can vary significantly.
When flu typically peaks here
The Southeast is the earliest-peaking HHS region in most flu seasons, with activity often reaching its high point in late November through December. In H3N2-dominant years — which tend to be early overall — the Southeast can peak 4–6 weeks ahead of the national peak. In late-season H1N1 years, the gap narrows, but the Southeast still tends to lead.
Florida is an exception within the exception. Its retiree-heavy coastal counties sometimes show activity later than the rest of the state, driven less by school-age spread and more by seasonal migration patterns — snowbirds arriving from the North in November and December can introduce strains circulating in other regions. Orlando and the central I-4 corridor, with its tourism density, tracks more like Atlanta than like Miami.
The Appalachian sub-region — eastern Kentucky, western North Carolina, eastern Tennessee — often peaks slightly later than the coastal metro areas, with terrain and lower density slowing spread. Rural Mississippi also lags the Atlanta-Charlotte-Nashville metro corridor by one to two weeks.
What drives Southeast flu patterns
Early school calendars. Most Southeastern states return K-12 students in late July or early August — three to five weeks before schools in the Northeast and Midwest. Children are the primary community transmission vector for flu; when they return to school earlier, community spread starts earlier. The data consistently shows ILI rates beginning to rise in the Southeast in September and October, while other regions are still flat.
Year-round air conditioning culture. The South's summer heat means air conditioning runs from April through October — the same forced-air indoor environments that concentrate respiratory viruses in winter exist year-round in the Southeast. The seasonal threshold for "going indoors" is effectively absent here.
Large metro hubs as accelerants. Atlanta, Charlotte, Nashville, and Raleigh are among the fastest-growing metro areas in the country. High in-migration, dense office districts, and major airport hubs (Hartsfield-Jackson is the world's busiest) accelerate both introduction and spread of new strains.
Healthcare access gaps. Mississippi, Alabama, and rural Kentucky consistently rank near the bottom of national health metrics. Lower vaccination rates and less access to primary care mean flu spreads further before people seek treatment — which shows up in ILI data as sustained elevation rather than a sharp peak-and-decline.
Recent seasons in HHS Region 4
Regional peak timing and severity can vary substantially from the national picture. The table below shows Region 4-specific peak months and severity for recent seasons, based on CDC FluView regional ILI data.
| Season | Regional peak | Dominant strain | Severity | Notable |
|---|---|---|---|---|
| 2024–25 | November–December | H3N2 / H1N1 | Very High | Among first regions nationally; Georgia and Tennessee went High in November |
| 2023–24 | December | H1N1 | Moderate | Early onset for Region 4; moderate severity despite early start |
| 2022–23 | November–December | H3N2 | Very High | Severe early season; Southeast led national tripledemic surge |
| 2021–22 | January | H3N2 | High | Late by Region 4 standards; post-COVID immune debt likely factor |
| 2019–20 | December–January | H1N1 | High | Early onset; ended with COVID-19 in March |
The Southeast is the nation's early warning system. When Region 4 crosses into High in November or December, the national peak is typically 4–8 weeks away. Thanksgiving travel accelerates the spread from the South to the rest of the country every year — it's visible in the ILI data two weeks after the holiday. Track the current season nationally. →
How to use this data
The live activity level above reflects the most recent week of CDC ILINet data for Region 4. There is always roughly a one-week lag between real-world conditions and published numbers — providers report weekly, the CDC publishes Thursdays, and this page reflects those numbers. During a rapidly rising season, treat the current level as a floor.
The ILI percentage is the share of outpatient visits attributed to influenza-like illness across all ILINet reporting providers in the region. It is not a case count and does not capture people who don't seek care. In regions with lower healthcare utilization rates (rural areas, communities with limited access), ILI percentages tend to understate true community activity.
For the most complete picture of the current season — including strain typing, lab positivity trends, and hospitalization data — the IsItFluSeasonYet homepage shows all of this in context. The regional activity shown here is the same data source as the homepage's region breakdown.