Part of Whitehorse Road has been shut after the wind off part of a supermarket roof, leaving pieces dangling dangerously.
Police have closed the road between Northcote Road and Windmill Road after the stormy weather ripped off sheets from the roof of the Tesco Express store.
London Fire Brigade are also on the scene.
Officers from Croydon fire station responded to calls about a precarious building at 3.30pm.
They requested specialist equipment including an aerial platform ladder to help make the damaged store safe.
Bus routes 50, 75, 157, 450, 468, and X68 are being diverted.
Smitham Bottom Lane in Woodcote, Purley, is partially blocked by a tree felled by the wind.