A summer norovirus wave is active across the United States right now. Surveillance data shows elevated activity in at least 12 states, with Utah, Texas, Ohio, and North Carolina leading in reported case counts.
If you have been hearing about a stomach bug going around, you are not imagining it. Norovirus typically peaks in winter. Summer 2026 is producing an unusual warm-weather surge driven by high crowd density, restaurant and camp exposures, and cruise ship outbreaks. Here is what the data shows.
Which States Are Most Affected Right Now
Based on real-time surveillance data, these states are showing the highest norovirus activity as of early July 2026:
High activity:
- Utah: The most active state in Virus Watcher's surveillance feed, with reports concentrated along the Wasatch Front
- Texas: Widespread reports across Dallas, Houston, and San Antonio metro areas
- Ohio: Cleveland and Columbus showing elevated signals
- North Carolina: Multiple reports across the Triangle and Charlotte regions
- Pennsylvania: Philadelphia-area clusters and summer camp exposures
Elevated signals:
- Maryland, Colorado, Iowa, Wisconsin, Massachusetts, Tennessee, Arizona
Massachusetts health officials have specifically warned of surging norovirus cases at summer camps and restaurants in the Boston area. Boston-area facilities have been among the hardest hit as the summer cruise and camp season peaks.
Why Summer 2026 Is Different
Norovirus is primarily a winter illness, but summer 2026 is producing above-average activity for several reasons:
Cruise ship clusters: By June 2026, four major gastrointestinal illness events on cruise ships had already triggered mandatory CDC federal notification thresholds for the year. The MV Hondius hantavirus outbreak in May drew attention to cruise ship disease risks, and norovirus has followed a similar pattern on other vessels.
Camp and restaurant exposures: Summer camps and outdoor dining create the same high-contact, shared-surface conditions that drive winter outbreaks. Contaminated food surfaces and inadequate handwashing remain the primary transmission routes.
Oyster and shellfish link: Several early 2026 clusters were traced to oyster harvests from British Columbia and Washington state waters. Shellfish filter large volumes of water and can concentrate norovirus from contaminated sources.
How to Tell If It Is Norovirus
Norovirus symptoms typically appear 12 to 48 hours after exposure and include:
- Sudden onset of nausea and vomiting
- Watery diarrhea (non-bloody)
- Stomach cramps
- Low-grade fever, headache, body aches
Symptoms usually last 24 to 72 hours. Most healthy adults recover without medical treatment, but dehydration is the main risk, particularly in young children, the elderly, and immunocompromised individuals.
When to seek care: Seek medical attention if you cannot keep fluids down for more than 24 hours, if there is blood in stool, signs of severe dehydration (dizziness, no urination, dry mouth), or if symptoms persist beyond three days.
What the Wastewater Data Is Showing
Wastewater surveillance is one of the earliest indicators of norovirus activity, detecting viral particles in sewage before clinical cases peak. Virus Watcher integrates national wastewater surveillance data from the CDC's NWSS program, which monitors more than 1,200 sites covering approximately 45 percent of the US population.
Current wastewater signals are consistent with elevated community circulation in the affected states. Utah and Texas showed wastewater anomalies before the current case surge became visible in reported data, which is the early warning pattern the surveillance system is designed to detect.
How Long Will This Last
Summer norovirus surges typically peak 4 to 6 weeks into the season and then decline as temperatures drop and outdoor gatherings become less frequent. Based on current trajectory, the peak of this wave is likely in July, with activity declining into August.
However, back-to-school season in August and September typically brings a secondary wave as children return to classroom settings. Parents should watch for reports of illness clusters at their children's schools starting in late August.
Track It in Real Time
Virus Watcher monitors norovirus activity across all 50 states continuously. You can track current reports for your state and set up alerts to be notified when activity changes.
- Norovirus in Utah
- Norovirus in Texas
- Norovirus in Ohio
- Norovirus in North Carolina
- Norovirus in Pennsylvania
- View all norovirus state tracking
Download the Virus Watcher app to get push alerts when norovirus activity rises in your area.
