Humberto — 2025

Humberto formed from a tropical wave that left the west coast of Africa around 18–19 September and became a tropical storm by 1200 UTC 24 September about 525 nautical miles east-northeast of the northern Leeward Islands. The storm moved generally west-northwest, slowed briefly when a nearby trough weakened the ridge, then resumed west-northwestward motion. Humberto underwent rapid strengthening late on 26 into 27 September, reached peak intensity on 27–28 September, turned northwest and then northward, weakened as it moved over cooler waters and under increasing wind shear, and became an extratropical cyclone by 1200 UTC 1 October about 230 nautical miles north of Bermuda before dissipating later that day. Humberto did not make landfall. It passed well north of the Leeward Islands and stayed well to the west of Bermuda; a Tropical Storm Watch was issued for Bermuda on 28 September but was discontinued the next day when attention shifted to nearby Hurricane Imelda. No sustained tropical-storm-force winds from Humberto were recorded on land, though weather stations on Bermuda measured gusts up to 36 knots on 30 September–1 October. The maximum sustained wind speed for Humberto was estimated at 140 knots (161 mph) from 1800 UTC 27 September through 0000 UTC 28 September, corresponding to a Category 5 hurricane on the Saffir–Simpson scale. The best estimate of the lifetime minimum central pressure at peak intensity is about 918 millibars, with some uncertainty because no in-situ measurements were taken at the exact time of peak intensity. Storm surge and heavy rainfall impacts on land were minimal because Humberto remained over the open Atlantic. Ship and buoy reports recorded gale and hurricane-force winds offshore (for example, buoy 41044 reported 42-kt winds and pressure 999.3 mb on 27 September), and two Bermuda stations observed gusts to 36 kt. No specific storm surge heights or large rainfall totals on named islands, counties, or cities were reported in association with Humberto. There were no reports of damage or casualties—no direct or indirect deaths—linked to Humberto. The greatest effects were marine: strong winds and hazardous seas reported by ships and buoys offshore and gusts on Bermuda. Humberto was notable for its rapid intensification from a 60-kt tropical storm to a 140-kt Category 5 hurricane in about 42 hours, an unusually long double-eyewall structure during a slow eyewall replacement cycle, and for being unusually close to Hurricane Imelda; their closest approach was the second-closest pair of Atlantic hurricanes in the historical HURDAT record and the closest since the start of the satellite era. Forecast track guidance performed well overall, but intensity forecasts underpredicted the rapid strengthening and later overpredicted how slowly Humberto would weaken.