Methodology

Version 1.0 of the Global Tropical Cyclones site, completed 21 July 2026.

Sources

North Atlantic, Northeast/Central Pacific: NHC/CPHC HURDAT2 best track.
Northwest Pacific: JTWC best track, via NCEI's IBTrACS archive (JTWC's own site isn't reliably reachable by an automated pipeline, but IBTrACS mirrors JTWC's operational values unchanged, tagged per-fix by source agency).
North Indian, South Indian, South Pacific: JTWC best track (as above), supplemented where JTWC has no record for a fix by two other sources IBTrACS carries alongside it: NCAR's ds824 archive (through 1980) and C. Neumann's Southern Hemisphere/ Indian Ocean historical compilation (through 2007). JTWC's own area of responsibility for these three basins wasn't formalized until 1985, so before then a large share of storms have no JTWC record at all -- ds824/Neumann fill that gap rather than JTWC's absence being read as "no storm." Per fix, whichever source reports the highest eligible wind is used (that source's own position and status, not a blend). Eastern Pacific was evaluated for the same treatment and doesn't get it: ds824's Eastern Pacific winds track HURDAT2's own within 0.01 kt on average pre-1970, and Neumann has no Eastern Pacific coverage, so neither source can improve on HURDAT2's existing record there.

Named Storm (NS): peak 1-minute sustained wind ≥ 34 kt while in a tropical or subtropical stage.
Hurricane/Typhoon (H): peak wind ≥ 64 kt.
Major Hurricane (MH): peak wind ≥ 96 kt (Category 3+).
Intense Hurricane (IH): peak wind ≥ 113 kt (Category 4+).
Category 5 (C5): peak wind ≥ 137 kt.
Storm days: accumulated 6-hourly synoptic fixes at or above a threshold, divided by 4.
ACE: sum of (wind speed in knots)² × 10^-4 over all synoptic fixes at or above 34 kt.
Hurricane landfalls: detected independently of each source's own landfall flag, following Weinkle, Maue & Pielke Jr. (2012) -- a storm's center crossing a coastline (islands under 50 km² excluded as noise), with landfall intensity taken as the max of the landfall fix's wind and the fix immediately before it, to capture a storm's peak just ahead of land-based weakening. Unlike that paper, which keeps only a storm's single most intense landfall, this site counts every landfall a storm makes. MH/IH/C5 landfalls are the same fixes at ≥ 96/113/137 kt respectively -- the same cumulative convention as the storm counts above, so a major-hurricane-strength landfall counts toward H, MH, and (if applicable) IH/C5 landfalls alike.

Storm counts are attributed to the basin/season a storm formed in; storm days, ACE, and landfalls are attributed to wherever the storm actually was, so a storm that crosses basins contributes to more than one basin's days/ACE/landfalls without being double-counted in basin storm counts.
Central Pacific (CPHC) storms are folded into the Northeast Pacific basin rather than shown separately.
Southern Hemisphere basin seasons (South Indian, South Pacific) run July-June and are labeled by the year the season ends in, following JTWC/BoM convention -- unlike the calendar-year seasons used for the Northern Hemisphere basins.
JTWC-based counts (Northwest Pacific, North Indian, South Indian, South Pacific) differ from JMA/IMD/BoM-based figures published elsewhere (e.g. Wikipedia), since JTWC uses its own operational criteria. This is expected, not an error.
Basin data coverage begins at different years (North Atlantic 1851, Northeast Pacific 1949, Northwest Pacific 1945, North Indian/South Indian/South Pacific back to 1877-1911 via ds824), so Global/hemisphere totals before ~1980 reflect incomplete global coverage, not a quiet era worldwide.
North Indian/South Indian/South Pacific storm counts before ~1990 are noticeably higher than in sources that only use JTWC -- this is the point of the ds824/Neumann supplementation above (JTWC alone misses roughly 60-90% of storms in this era for these three basins), not a data-quality regression.