The fireworks, flags and hot dogs are at the ready as New York gets set to celebrate the Fourth of July in spectacular style.

America’s greatest fireworks show — featuring 40,000 shells synchronized to a spectacular music score — will be set off at about 9:25 p.m. over the Hudson River between West 24th and West 50th streets.

Macy’s, the show’s sponsor, says everything is ready to go. By yesterday, the fireworks were loaded on their four barges, and the impresarios at Pyro Spectaculars were prepared to bathe the West Side and Jersey in fiery light.

If you’re headed out to watch the show, you might want to bring an umbrella, just in case. Thunderstorms are possible after 10 p.m., AccuWeather forecasters say.

But you need not worry about rain dampening the fireworks — the display is “waterproof,” a Macy’s spokesman said.

Some thunderstorms are possible during the day, but mostly, it’ll be sunny, with temps peaking at 94 degrees — a decent beach day.