Sudden bursts of punishing wind spun havoc at Macy's Thanksgiving Day Parade yesterday, as many of the parade's signature helium-filled balloons were damaged and as four spectators were hurt when one of the giant balloons struck a lamppost, plunging the top part of it into the crowd. Two people were hospitalized with severe head injuries.

The accident was a strange and grim counterpoint to a sunny day of high festivity in which most of the two million spectators were far away from the accident and had no idea it happened. They cheered, clapped and squealed as 14 marching bands from 13 states strutted past, as 600 clowns and 1,200 cheerleaders enthusiastically did their thing, and most emphatically, as the immense six-story balloons of instantly recognizable cartoon characters glided past the brick, glass and concrete of Manhattan.

Only, at times, the balloons were not gliding but instead were careering as their handlers on the ground struggled to keep control in winds that reached as high as 43 miles an hour. For a while, the balloons seemed to be falling like flies. Barney suffered extensive damage and had to be removed at 51st Street. The Pink Panther succumbed at 42d Street. Quik Bunny and the Cat in the Hat limped away at 36th Street.

There was high drama as the balloon handlers and the police tried to control the airborne chaos. As the Pink Panther lurched about, while simultaneously imploding, a police inspector shouted, ''Somebody give me a knife, quick!'' An officer quickly handed him a 5-inch-long knife and he punched a hole through the feline's tail, a move that almost immediately stabilized the balloon.