What the Hurricane Cone of Uncertainty Really Means
The "cone of uncertainty" is the most-viewed — and most-misread — graphic in hurricane forecasting. Drawn by the National Hurricane Center around a storm's forecast track, the cone represents the probable path of the storm's center, sized so that, based on the last five years of forecast errors, the center stays inside the cone about two-thirds of the time.
Read that again: one storm in three leaves the cone at some point. And the cone says nothing about the storm's size. Hurricane-force winds can extend 50+ miles from the center and tropical-storm-force winds 200+ miles — far beyond the cone's edges. Storm surge, rain flooding, and tornadoes routinely cause damage well outside it.
The mistake that gets people hurt
Every hurricane season, people just outside the cone's edge decide they're safe and stop preparing. Forecasters call this the "edge-of-the-cone" problem. The cone narrows near the storm's current position and widens with time — day 4 and 5 positions are genuinely uncertain by 150–200 miles either way.
How to use the cone well
- If you're anywhere inside or near the cone, prepare. "Near" means within a cone's width of the edge.
- Watch the trend across advisories, not a single frame. Track shifts of 50 miles between advisories are normal.
- Pair the cone with watches and warnings — those are drawn for actual hazards at your location (see watch vs. warning).
You can see the live cone for any active storm on our live tracking map, drawn from the same NHC data, updated every advisory.
FAQ
What percentage of storms stay inside the cone?
About two-thirds. The cone is sized from the past five years of official track errors so that the storm center remains inside it roughly 60–70% of the time — meaning one storm in three leaves the cone at some point in its forecast.
Does the cone show where damage will occur?
No. The cone only maps the probable track of the storm's center. Winds, surge, and rain extend far beyond it — often by 100 miles or more on each side.
Why does the cone get wider over time?
Forecast uncertainty grows with lead time. Five-day center positions have historically been off by 150–200 miles on average, so the cone flares outward to reflect that.