Summer Hazard Odds
At Vegas Insider, we analyze odds for a living. So we turned that lens on summer vacation. We ranked 42 of the most visited US destinations by implied hazard risk across four categories: shark attacks, lightning, jellyfish, and heat illness.
Destinations were chosen based on National Park Service attendance data, coastal visitor volumes, and editorial judgment. These are the places Americans actually go in summer.
Each destination is scored only on the hazards that apply to it. The Grand Canyon has no shark or jellyfish risk, so it ranks on lightning and heat alone. Two extreme risks can outscore four moderate ones. The number of applicable hazards is shown with every result.
How we scored each destination
Shark
ISAF historical attack counts divided by estimated coastal visitor volumes. Normalized against Florida, which leads all states.
Lightning
NOAA state-level casualty rates per million people, adjusted for summer seasonality (74% of annual strikes occur June through August) and scaled to a 2-week window.
Jellyfish
NOAA exposure tier classifications based on species presence, seasonal activity, and reported sting frequency at each location.
Heat
CDC Heat and Health Tracker tier ratings, anchored to Arizona's documented 2.9% heat illness ER visit rate in peak summer months.
Key Findings
What the data reveals
Shark
New Smyrna Beach ranks #1 nationally
Volusia County has recorded more unprovoked attacks than any other stretch of coastline in the world. Your risk is still just 0.00015% per trip, but that is 7x the US national average.
Lightning
Rocky Mountain NP outranks every beach
Colorado’s exposed terrain gives Rocky Mountain NP a higher lightning score than any coastal destination. Florida leads all states with 79 CDC-recorded deaths from 2006 to 2021, but the Rockies are a close and underappreciated second.
Jellyfish
Hawaii’s box jellyfish arrive on a lunar calendar
Waikiki and the Florida Keys both hit the maximum exposure score. Hawaii’s box jellyfish surge predictably 9 to 10 days after each full moon. Florida deals with Portuguese man-of-war year-round. Peak risk runs as high as 0.8% per trip.
Heat
Grand Canyon hits 2.9%, the highest risk in the dataset
Arizona and Nevada score the maximum on heat. A 2.9% chance of heat illness per 2-week trip is the highest risk in this dataset, straight from CDC data. Heat is the only hazard here that competes with everyday life.
