Which Atlantic hurricane had the largest diameter (gale-force wind field) on record?

Hurricane Sandy had the largest gale-force wind field recorded for an Atlantic hurricane in the modern observational record. Its tropical-storm-force, or gale-force, winds expanded to roughly 1,150 miles across as the storm grew unusually broad in late October 2012. The record refers to the diameter of winds of at least 34 knots, not the size of Sandy’s eye or the area experiencing hurricane-force winds.

Sandy became exceptionally large as it moved northward over the western Atlantic and interacted with a mid-latitude weather system. It also absorbed energy from the warm Gulf Stream while merging with colder continental air. That unusual hybrid evolution helped spread strong winds over a vast area, even as Sandy’s maximum sustained winds were lower than those of many smaller, more intense hurricanes.

A common mix-up is Hurricane Olga, which was described as the largest Atlantic tropical cyclone by gale-force diameter at the time of its 2001 season. Sandy surpassed that benchmark in the longer satellite-era record beginning in 1988. Its immense wind field contributed to widespread coastal flooding and storm surge from the Carolinas through New England, including the catastrophic New Jersey and New York impacts.