About 400,000 customers were still without power in Maine, New Hampshire and Vermont on Friday after a powerful storm system brought springtime snowfall to northern New England.

Here are the main things to know on Friday.

• The peak of the nor’easter had largely passed by Friday morning. The National Weather Service said it expected the storm to gradually weaken over the weekend “but it will take its time,” with widespread wet snow mixed with rain in lower elevations expected to continue through Friday. About four to eight inches of new snow may accumulate in some areas.

• Power was slowly coming back on across the region after the storm left nearly half a million customers without power. But progress was slow as of Friday morning: In Maine, more than 280,000 customers were still without power, according to PowerOutage. US; more than 100,000 in New Hampshire and about 15,000 in Vermont.

• More than a foot of snow fell over much of the region. In York County, Maine, just south of Portland, an observer for the National Weather Service reported nearly 20 inches as of Thursday night.

David Roth, a meteorologist with the Weather Prediction Center in College Park, Md., said that the storm was expected to linger in the region.

“Most of the time, nor’easters just move steadily up the coast,” he said. “This one stalling for a couple days is not great because it also brings with it the threat of coastal flooding.”

Air travel was also disrupted. More than 400 flights within, to or from the United States were canceled on Thursday afternoon, according to FlightAware; many of them were in Boston. That number had jumped to 500 by Friday morning. More than 8,500 flights were delayed.

While some New England residents may be caught off guard by the nor’easter, just days after the Easter holiday and during spring break for many school districts, Rodney Chai, the lead meteorologist with the Weather Service in Burlington, Vt., said this week that snow in April was not uncommon.

“It may come as a little bit of a shock to people because we have had a stretch of nice springlike weather and this winter has been anomalously mild,” he said. “People might have gotten a little too comfortable.”

But things are looking up in time for the solar eclipse on Monday: It is expected to be in the mid-50s and sunny across northern New England.