Dense Fog in the United States

How dangerous are Dense Fog events in the U.S.?

NOAA's Storm Events Database has catalogued 8,867 dense fog events across 41 states and territories between 2015 and 2025. The cumulative human toll is 164 fatalities and 542 injuries, and the financial footprint reaches $16.7M in combined property ($16.7M) and crop ($0) damage. On a per-fatality basis this places dense fog events at a very high severity tier relative to other tracked hazard types in the NOAA catalog.

Geographic exposure is heavily concentrated in a handful of high-severity states. The three states absorbing the largest share of events are CA (1,820 events, 59 fatalities), IL (1,339 events, 6 fatalities), KY (1,222 events, 1 fatalities), reflecting both physical geography (coastal exposure, plains corridors, terrain) and dense population sitting directly in harm's way. At the other end, states such as MS, SC, OK report far fewer events, a genuinely rare event outside the leading states, not merely an underreported one.

The year-to-year record shows real volatility around a high baseline. The peak year on record was 2025, logging 1,264 events and $138.0K in property damage in a single calendar year. The most recent year in the dataset is 2025 with 1,264 events recorded. Across the full 11-year window, annual event counts reflect seasonal climate cycles (ENSO phases, active vs. quiet severe-weather years) and long-term shifts tied to a warming climate both help explain the swings.