It's a rainy start to Christmas in Sydney, but the showers are expected to disappear after lunch and it will be hot by Friday.

Senior Weatherzone Meteorologist Jacob Cronje said temperatures were unlikely to exceed 25 degrees anywhere in Sydney on Christmas Day.

A swims at Bondi Beach as an afternoon storm approaches on Christmas Eve. Bondi is forecast for a top of 20 degrees on Christmas Day. Credit:Jessica Hromas

"We are looking at clearing showers later this morning into midday, but conditions will remain partly cloudy and windy from the south, therefore quite cool," he said.

"We're looking at temperatures ranging in the 23 to 25-degree mark anywhere in Sydney, possibly reaching about 26 in places like Penrith."