Residents are being warned to steer clear of beaches and exercise routes this weekend, or risk further shutdowns, after crowds prompted the closure of beaches in Sydney's east on Friday days after they had reopened.

The closures come as Inner West Council mayor Darcy Byrne issued a warning to the population to stay away from the popular Bay Run pedestrian and cycling route this weekend.

"Go somewhere else," Cr Byrne said. "It's really important to do your exercise, [but] do it somewhere other than the Bay Run."

People jogging and walking on the Bay Run, Haberfield this month. Credit:Louise Kennerley

He said council staff would not hesitate to close the shared path, which was patrolled by mounted police on Thursday, if police and health authorities advised them to do so.