As Ida’s deadly waters receded Thursday from subway stations and roads, playgrounds and apartments, stunned residents of New York and New Jersey confronted their vulnerability now the old norms of weather no longer apply.

The remnants of a hurricane that first hammered distant New Orleans unleashed a torrent intense enough to kill at least 40 people across the Northeast, paralyze the nation’s largest and wealthiest city, halt its lifeblood transit system and conjure a future where residents and the economy are constrained by recurrent disasters.

In New York and its suburbs — which rebuilt power grids, subways and tunnels after 2012’s Hurricane Sandy flooded lower Manhattan — roads were closed, commuter rail was hobbled and hundreds of flights were canceled.