Portland can expect its first major snowfall of 2015 on Saturday, forecasters said.

The National Weather Service has posted a winter storm warning for the Maine coast and said the Portland region should get about 6 to 8 inches of snow by the time the storm moves out late Saturday night.

Meteorologist Margaret Curtis said the snowfall is expected to start in southern Maine by mid-morning, and be heaviest in the afternoon. By about 10 p.m., she said, the snowfall should be over.

Sunday is expected to be mostly sunny and breezy, with a high in the upper 20s. Curtis said a chance of light snow is in the forecast for Monday.

The same storm is expected to bring a messy mix of rain, snow and sleet to the Northeast’s major cities in what forecasters are calling the Interstate 95 corridor’s first brush with a significant winter storm this season.

The fast-moving storm system will travel up the eastern seaboard, creating “the potential for significant snow and ice” before moving out to sea off New England by early Sunday, the weather service said.

The biggest snowfall amounts are expected in southern New England, and forecasters warned that temperatures hovering near freezing could make for slippery driving conditions across the region.

“It’s kind of the first one, so it’s a good thing it’s happening this weekend,” said National Weather Service meteorologist Bill Simpson in Taunton, Massachusetts. “If this happened during a weekday, it could be really slow and messy.”