Tasmania weather: Flash flood warning for state's south and east

The weather bureau is warning of heavy rain and possible flash flooding in eastern and southern Tasmania.

The Bureau of Meteorology (BoM) issued a flood warning for the state's east and expected 20-40 millimetres overnight until mid-morning on Wednesday.

Senior forecaster Simon McCulloch said some areas may receive even bigger rainfall totals that could cause localised flash flooding.

"The likely high totals perhaps in the north-east would be around Gray and St Marys," he said.

"In the south, perhaps around the Huon Valley, maybe into other parts of the south-east around Nugent, Copping."

Brian Edmonds from the State Emergency Service warned drivers to take care on slippery roads.

"There is dirt and grime and some oil build up on roads," he said.

"It's usual during periods of warmer weather, and then the initial rain often produces very slippery conditions until it clears off."

The forecast prompted organisers to postpone the third round match at the Hobart tennis International.

Play will be rescheduled after court inspections on Wednesday morning.