Summerlike warmth will surge northward into the Ohio Valley by Wednesday and the mid-Atlantic states on Thursday.
The pattern will feature multiple days with highs well into the 80s F as far north as cities from Cincinnati to Pittsburgh and Washington, D.C., from the second half of this week into the start of May.
It is possible that some cities from this latitude on south can touch 90 on one or more days.
The weather will be a boon for warm season outdoor activities ranging from gardening and construction projects to recreational sports and sunbathing.
Those heading to the lake or beach for a swim should be aware that water temperatures are still dangerously chilly this early in the season. Ocean water temperatures along the mid-Atlantic coast range from the upper 40s to near 60.
Areas farther north from Chicago and Detroit to Cleveland, New York City will catch some warmth on occasion into early next. In this swath, temperatures will reach the 70s and could touch 80 during a spike on one or two days.
"Across the Great Lakes and New England, there will be frequent rounds of showers, that will prevent or limit the big warmup," according to AccuWeather Senior Meteorologist Brett Anderson.
Along the east coast of New England, including in Boston, another complicating factor will be episodes when a chilly wind blows in off the ocean.
"There can still be some brief spikes in temperature in between storm systems across the northern tier of the northeastern United States and adjacent Canada," Anderson said.
For people heading to the 2017 NFL Draft in Philadelphia and partaking in outdoor activities later this week, highs will be in the 80s most days from Thursday through Saturday. Lows most nights will be within a few degrees of 60.
Exactly how warm it gets in Philadelphia will depend on the amount of sunshine. Any thundershower activity is likely to be brief from Friday to Saturday.
At Louisville, Kentucky, workouts for the 2017 Kentucky Derby have begun. Highs will trend upward from the 70s through midweek to the upper 80s to near 90 this weekend. The Derby will be on Saturday, May 6. Cooler, more seasonable air may arrive by then.
The summerlike pattern will be brought on by a northward bulge in the jet stream. The jet stream is a river of air at the level in the atmosphere where jets cruise at.
South of the jet stream, temperatures are often much warmer than average.
As warm air bulges northward in the eastern U.S., cool air will dip southward in the West.
Near the west-to-east boundary of the chill and warmth, rounds of drenching rain and severe thunderstorms will riddle the Central states.