Sydney motorists have been reminded to brace themselves for life without the city's Harbour Bridge, for a few weekends at least.

The bridge will close from 10:00pm (AEDT) tonight until 5:00am on Monday while the roadway is resurfaced and water-proofed.

It is the first complete revamp for the roadway since the bridge opened in 1932.

The work is expected to take three weekends, weather permitting.

Trains will continue to cross the bridge and the bus lane will also remain open.

Brett Moore from the Transport Management Centre says disruption is unavoidable.

"We're expecting some congestion around the CBD and also roads leading in the city because of this closure of the Sydney Harbour Bridge," he said.

"That's why we're encouraging people to take advantage of public transport. There are extra trains operating from the north, there are extra buses as well. That's going to be the best way to get into the CBD this weekend.

"It's being done when the bridge has its least amount of work for the year and while there will be some disruptions to motorists, we're hoping it won't be too much."