Hurricane Sandy brought to New York much more wind than rain, and the greatest damage has been near the Atlantic Ocean, the Long Island Sound, and the two rivers. We all knew which neighbourhoods faced the most immediate danger – Battery Park, Red Hook, Rockaway – but it wasn’t until late last night, safe at home, that I realised the hurricane spelled trouble for most of the city’s art galleries, clustered together in Chelsea a block from the Hudson. I went down this morning. The water has receded (mostly – 21st Street was impassible today), but there’s still no power, and the damage is total. Every celebrity architect you can name has retrofitted one of these spaces, but they weren’t made to withstand this kind of onslaught. They’re low-slung warehouses, mostly, with garage doors at their entrances. The hurricane warped many of the doors; I saw a team of dealers trying to pry open a metal gate with a crowbar.

At Gagosian on 21st Street the water had reached waist height; they keep the blue chip art uptown, but through the gate I could see a Henry Moore on a plinth high enough to evade the flooding. The water seemed to have done the same at Gladstone – where an exhibition by Thomas Hirschhorn about the Costa Concordia shipwreck had just closed. 303 Gallery had its glass door blown in, and a whole wall had buckled. The worst damage seems to be on 19th Street, home to, among others, David Zwirner Gallery. Last night 19th was a river, and today I saw four photographs by James Welling still hanging on a pristine white wall gashed by an eye-level horizon of mud. The real question is what was in storage in the basement.

I bumped into a friend who works at one of the bigger galleries on 24th Street. They’d had three feet of water in the gallery, and he and four others were mopping up the aftermath. How bad is the damage, neighbourhood-wide? 'A couple hundred million dollars?' he estimated. Horrible, and it will take a week or two before the toll is clear – and yet, unlike many Americans, at least the galleries have insurance.