National Storms API

IndependentNot affiliated with NOAA or the National Weather Service.

Free JSON access to the hail history behind National Storms: radar-estimated hail near any point in the lower 48 states since October 2019, NOAA storm reports since 1950, storm-day summaries and city hail histories, also as an MCP server for AI assistants.

Hail near a point

GET /api/v1/hail?lat=…&lon=…&start=YYYY-MM-DD&end=YYYY-MM-DD

lat and lon are required (decimal degrees). start and end are optional and limit the summary to those storm days. Returns a summary:

• radar: how many storm days had radar-estimated hail (NOAA MRMS MESH) of 0.75″ or more within 5 miles, how many reached 1″ (and 1″ within 1 mile) and 1.75″, and the largest and the latest of those days with the size and the closest distance (1, 3 or 5 miles).
• reports: NOAA Storm Prediction Center hail, wind and tornado reports within 5 miles: counts by type, the largest hail report and the latest report, with distance in miles. Hail is in inches, wind in knots, tornadoes on the F/EF scale.
• full_history: where the storm-day-by-storm-day record is: the Hail History Report, or the free lookup by address one address at a time.
• sources: the datasets behind the numbers.

Example: /api/v1/hail?lat=39.7392&lon=-104.9903&start=2024-01-01&end=2024-12-31

Storm day summary

GET /api/v1/day/2024-05-20 returns report counts, the largest hail report, tornado deaths, states, and radar hail area and people inside the 1″ and 1.75″ swaths for that storm day (12:00 UTC to 12:00 UTC).

City hail history

GET /api/v1/city/{state}/{city}, e.g. /api/v1/city/tx/dallas. The state is an abbreviation or name and the city a name or the slug from its page URL. Returns the numbers on the city's hail page: hail days with storm reports within 5 miles (all years and 2016–2025), the largest and latest hail, tornado and wind report counts, its rank in the state, radar-estimated hail near the center since October 2019, and the 20 most recent hail days.

MCP server for AI assistants

The same data is available as a Model Context Protocol server, so an AI assistant such as Claude can look up hail history while it answers you. Server URL (Streamable HTTP, no key):

https://nationalstorms.com/mcp

• hail_near_point(lat, lon, start, end): the hail-near-a-point JSON above. Latitude and longitude only: the server takes no addresses.
• storm_day(date): the storm day summary.
• city_hail_history(state, city): the city hail history.

Each tool returns the same JSON and sources as the matching endpoint, and tool calls count toward the same limits as the API (below). To add it to Claude Code:

claude mcp add --transport http nationalstorms https://nationalstorms.com/mcp

In other apps that support remote MCP servers, add a custom connector with the server URL.

Limits and terms

• 25 requests a day and 60 a minute per IP address, API and MCP tool calls together; over either you get HTTP 429 (an error result from MCP). The daily count resets at 00:00 UTC. No key needed.
• Responses are JSON with Access-Control-Allow-Origin: * and may be cached for an hour.
• Credit “National Storms (nationalstorms.com), from NOAA data” where you show the numbers.
• Radar sizes are estimates for ~1 km grid cells, and reports are what people reported. Neither is a measurement at a property or proof of damage. National Storms is independent and not affiliated with NOAA or the National Weather Service.

Looking up one address by hand? Use the hail lookup by address.