Roads have reopened on Tasmania's east coast after hundreds of people were stranded by flash flooding, but forecasters say more heavy rainfall is likely in coming days.

Key points: Heavy rain closes roads, causes flooding

Heavy rain closes roads, causes flooding Houses inundated at St Marys

Houses inundated at St Marys More rain predicted in flood zones

More rain predicted in flood zones SES crews responding to calls

Hundreds of people were stranded by heavy flooding in the seaside towns of Orford and Triabunna on Tasmania's east coast when the only road out of town was inundated.

Glamorgan Spring Bay Council set up an emergency centre after people tried unsuccessfully to find accommodation in the area.

Council officials had managed to find accommodation for about 15 groups but were struggling to find more rooms because some hotels were flooded.

Greg Breen, who was trying to pass through Triabunna with his family, managed to secure the last room at the Tandarra Hotel.

"There's lots of people in Triabunna and accommodation is at a premium," he said.

"We made a lot of phone calls to see if we could get accommodation and there's lots of people here at the Tandarra tonight, the bar's full."

When flood levels receded enough to allow traffic through, the evacuation centre was closed.

State Emergency Service southern regional manager Mark Nelson said he was hopeful the worst was over.

"Heavy rains, from information I've gathered from the Bureau of Meteorology, should be easing sometime fairly soon, it was late afternoon to early evening they were predicting the bulk of the heavy rain should go through.

While some properties were inundated by flooding in the state's north-east, southern communities prepared for a downpour.

Loading

St Marys residents said they were used to some flooding but had not seen anything like the recent rainfalls.

Residents tried to minimise the damage after water broke down fences but many found themselves waist deep in water on the ground floor of their properties.

The local bakery was mopping up after being inundated.

More rain is forecast for Saturday.

Some roads remain closed and police have asked drivers to be cautious and check road closure alerts online.

Launceston received 85.8mm, a record for a single day, and the small town of Gray on the east coast has been hit with 220mm of rain over the same period.

State Emergency Service northern regional manager Mhairi Revie said crews were sandbagging and helping people prepare for the risk of further flash flooding over the next two days.

"People need to be prepared at the moment...it's not over yet and the more prepared people are, the less damage they'll have in the aftermath," she said.

Peter Skillern from the Farmers and Graziers Association said the rain could not have come at a worse time for poppy growers.

"Bearing in mind that there are still crops that need to be harvested, poppy crops and grain crops and rain on those will do them no good whatsoever," he said.

"Potentially a significant amount of rain would destroy those crops."

Dennis Betts from Longford Berries told ABC local radio his entire crop of strawberries, raspberries, gooseberries and blackberries was shredded by a hailstorm on Thursday.

"A bit of a shock and a disappointment but by the same token how can I be churlish about that sort of weather when everyone in the state has been crying out for decent rainfall," he said.