Data sources & licences

This site is built entirely on open data and open-source software. Thank you to everyone who collected, shared and maintains it. Here is exactly what we use and the licence each part comes with.

Data version

NOAA NCEI IBTrACS v04r01, downloaded 2026-10-12, data to 2026-10-11 00:00: 13,248 storms (159 provisional), 1842 to 2026. Census cartographic boundaries 2020. Natural Earth 10 m.

Last refreshed

2026-10-12

Software

The map is drawn with MapLibre GL JS and PMTiles, and the site is built with Astro. These are open-source projects under their own licences.

Using our images and embeds

Images you download from the map and the embed code both carry the credits above. Please leave them in place.

The storm record in numbers

The map is built from the IBTrACS v04r01 "ALL" file, downloaded on 2026-10-12 (the file was last modified Sun, 11 Oct 2026 09:03:08 GMT). The last observation in it is 2026-10-11 00:00. It gives 13,248 storms and 352,574 six-hourly positions. The file's SHA-256 checksum is 0bfaf113e3c1980a…. IBTrACS is refreshed every week and overwritten in place, so the date above is what identifies the copy we used.

159 storms of 2025 and 2026 are provisional: they are not yet in the final best track, and the map and pages label them as such. 5,569 storms (42%) have no wind speed in either source, mostly Indian and Pacific storms before the 1950s, and show as unknown intensity.

How the records are counted

• A storm affects a region when its track (straight lines between fixes) passes within 50 km of it while tropical.
• USA_WIND (1-minute) where present, else the WMO agency wind divided by 0.88 to a 1-minute equivalent (WMO/TD-1555); the agency is recorded. Storms with neither are unknown.
• Named storms with peak category 3 or more, plus a curated list.
• IBTrACS main tracks plus provisional tracks (2025 to 2026, flagged), 6-hourly fixes only.
• Fixes with nature ET or DS do not count for peak intensity, seasons or region joins.
• A place page counts every storm whose track comes within 50 km of the place. A US county, a country or a region gets a page that search engines can index once it has at least 3 storms, and so does a season. Pages below that still exist but are marked noindex and left out of the sitemap.
• Stages of a storm that are post-tropical (extratropical) or only a disturbance are drawn, but they are not counted for peak intensity, seasons or place counts.

Data caveats

• Pre-satellite estimates. Records before about the 1960s rely on ships, coastal stations and aircraft, so positions and intensities are estimates and some storms are missing. Intensity figures before the 1950s in the Indian and Pacific oceans are largely absent.
• Wind-averaging conventions. US agencies (the National Hurricane Center, the Central Pacific Hurricane Center and the Joint Typhoon Warning Center) report 1-minute sustained winds. Most other forecast centres use 10-minute winds, and the India Meteorological Department uses 3-minute winds. Dividing a 10-minute wind by 0.88 gives a 1-minute equivalent (World Meteorological Organization guidance, WMO/TD-1555), and that is what this site does where no US figure exists. The agency behind each storm's peak is named on its page, and a storm's own national category can therefore differ from the category shown here. For storms with a regional centre figure, such as Typhoon Haiyan (2013, 125 kt on the Japanese 10-minute scale, 170 kt on the US 1-minute scale), both are shown.
• Straight lines. A track joins six-hourly positions with straight lines. The real path curved between them, and a storm's winds and rain reach well beyond its centre.
• Landfalls are approximate. A landfall here is the first tropical position over land after time at sea, so it is at most six hours from the real event.

Where the US agency figures come from

IBTrACS merges the best tracks of several agencies. Its US fields carry the National Hurricane Center's HURDAT2 records for the Atlantic and eastern Pacific and the Joint Typhoon Warning Center's records elsewhere. We use those US fields first, so HURDAT2 reaches this site through IBTrACS rather than as a separate download. The busiest basin by storm count is WP.

Citing the storm data

NOAA asks that both papers be cited: Knapp, K. R., M. C. Kruk, D. H. Levinson, H. J. Diamond and C. J. Neumann, 2010, The International Best Track Archive for Climate Stewardship (IBTrACS): Unifying tropical cyclone best track data, Bulletin of the American Meteorological Society, 91, 363-376, doi:10.1175/2009BAMS2755.1; and Gahtan, J., K. R. Knapp, C. J. Schreck, H. J. Diamond, J. P. Kossin and M. C. Kruk, 2024, International Best Track Archive for Climate Stewardship (IBTrACS) Project, Version 4r01, NOAA National Centers for Environmental Information, doi:10.25921/82ty-9e16.