About the Data

The National Hurricane Center (NHC)is a division of NOAA's National Weather Service and the U.S. government's official authority for tropical cyclone track and intensity forecasts in the Atlantic and Eastern North Pacific basins. NHC has been issuing hurricane forecasts since 1898 and is headquartered in Miami, Florida.

NHC forecasters use data from multiple observational systems: NOAA and Air Force Hurricane Hunter aircraft flying directly into storms, geostationary and polar-orbiting satellites, Doppler radar networks, ocean buoys and ships, and an ensemble of numerical weather prediction models. No private or commercial forecast service has access to observational inputs comparable to what NHC uses.

GetStormRisk displays only NHC data and never substitutes its own forecasts. All forecast data on GetStormRisk originates from the National Hurricane Center (nhc.noaa.gov), operated by NOAA. GetStormRisk is not affiliated with NHC or NOAA.

NHC issues advisories on the following schedule:

• Routine advisories: Every 6 hours at 11 AM, 5 PM, 11 PM, and 5 AM EDT/AST for active named storms.
• Near-landfall advisories: Every 3 hours when a storm is within 24–36 hours of landfall (intermediate advisories added between routine issuances).
• Special advisories: Issued outside the routine schedule when significant and sudden changes occur — such as rapid intensification events or major track shifts.
• Tropical weather outlooks: Issued 4 times per day to monitor disturbances that have not yet organized into named storms.

GetStormRisk ingests the NHC CurrentStorms.json endpoint and associated GIS cone/track files every 15 minutes during active storms, and every 6 hours during the off-season. This ensures GetStormRisk reflects NHC updates within minutes of issuance.

The NHC forecast cone — officially the “cone of uncertainty” — is sized based on the average track forecast errors over the previous 5 years. According to NHC, the cone is constructed so that the storm's center will remain within it approximately 70% of the time based on historical model performance.

This means roughly 30% of historical storms have had their center exit the cone before the forecast period ended. The cone does not represent a 100% probability boundary. It also does not represent the full extent of the storm's wind field, rain, or storm surge — all of which can extend hundreds of miles beyond the cone's edges.

The cone widens over time because forecast uncertainty compounds. The 1-day forecast cone is much narrower than the 5-day cone. NHC publishes annual verification statistics detailing average track and intensity errors by forecast day.

The forecast track is the single most likely path of the storm's center — a line of forecast positions at 12-hour intervals. The forecast cone is the region of uncertainty around that track line. Both are published by NHC as GIS files.

GetStormRisk renders both: the track as a line of waypoints and the cone as a polygon overlay. Distance-to-track measurements on GetStormRisk use the nearest-point distance from an address to the forecast track line (not to the center of the cone).

When you enter an address on GetStormRisk, the system performs two calculations using the latest NHC advisory GIS data:

1. Point-in-cone: Tests whether the geocoded address coordinates fall within the NHC-published 5-day forecast cone polygon. This uses standard geographic point-in-polygon computation against the official NHC GeoJSON.
2. Distance-to-track: Computes the minimum great-circle distance in miles from the address to any segment of the forecast track line. This gives context even when the address is outside the cone.

Wind category estimates at a given distance are rough approximations based on typical wind radii from historical storms. They are not official NHC products and should not be used for safety decisions. Storm surge risk depends on local coastal geometry, elevation, and the storm's approach angle — none of which GetStormRisk models. Storm surge maps are available from NOAA's P-Surge model.