AUGUSTA — With some Maine residents already stuck in their homes Monday because of seasonal flooding from river ice jams, a storm in the overnight forecast threatened to make things worse, with as much as 3 inches of rain in some places.

Central Maine was expected to get hit the hardest, with the heaviest rains likely causing some minor flooding in Augusta, Hallowell, Gardiner and other areas, said meteorologist Tom Hawley of the National Weather Service in Gray. At the same time, strong winds could cause problems along the southern Maine coast, Hawley said.

“We are in the middle of some of our highest tides of the year,” he said. “With the wind blowing that water up on shore, there could be some coastal flooding and beach erosion,” he said.

The National Weather Service has placed much of the southern half of the state under a flood watch from Monday night through Wednesday morning. That includes Androscoggin, Franklin and Oxford counties.

Some residents in Washburn were already stuck in their homes because the roads were flooded and impassable, although that’s not unusual for this time of year, said Darren Woods, director of the Aroostook County Emergency Management Agency.

He said officials are worried about the impact the rains could have in places where ice jams remain in waterways near St. Francis, Grand Isle, Washburn and Allagash.

“We will be watching the northern rivers in particular very closely to see what rise we get in the rivers as a result of the rain,” said Mark Hyland, operations and response director for the Maine Emergency Management Agency. “When you get a jump in the river elevation that tends to create more ice jams and create bigger problems.”

Officials warned residents to keep their children away from the floating ice along the river banks and to avoid flooded roads, even if the water doesn’t appear to be that deep.

“People, for whatever reason, continue to drive around barricades and that’s really not a safe thing to do,” Woods said. “The water may look stagnant, but there’s quite a bit there and it can sweep a vehicle away quickly.”

Rain was increasing in areal coverage across New Hampshire, and that trend was working into Western Maine. pic.twitter.com/zQWxPE6FwQ

— NWS Gray (@NWSGray) April 20, 2015