Parts of this week will feel more like summer across the Midwest and Northeast with the warmest days of 2015 set to unfold.
"The [warmth this week] will be far from a heat wave," stated AccuWeather.com Meteorologist Brian Lada and a cool shot will prevent the warmth from dominating the entire week.
However, summerlike days will still win out over more seasonable days when the week is complete.
Building warmth to end the weekend will give way to the warmest day so far this year throughout the Northeast and parts of the Ohio Valley on Monday.
Highs in the 80s will be widespread across the Ohio Valley and along the I-95 corridor, northward to New York City. Boston has not cracked the 70-degree mark since late last October, but will soar past that threshold on Monday.
"Streams and ocean water temperatures are dangerously chilly this time of year," AccuWeather.com Senior Meteorologist Alex Sosnowski warned anyone contemplating entering the water to beat the warmth.
"Near-shore Atlantic water temperatures are currently in the 40s and 50s," Sosnowski added.
Winds blowing off these chilly waters will keep actual temperatures at south-facing beaches cooler.
Residents who are not a fan of the summer warmth can also await the passage of a cold front that bring some cooling by midweek.
The front, accompanied by showers and thunderstorms, will first usher cooler air across the northern and western Great Lakes on Monday, then the eastern Great Lakes and New England on Tuesday.
After the warmth hangs on through Tuesday, a few degrees will get shaved off Tuesday's high for Wednesday from New York City to Philadelphia to Baltimore.
The cool shot will return temperatures back to normal in the Great Lakes, but "Highs at midweek will remain above normal for early May [in the Northeast]," added Lada.
Similar to the summer warmth starting this week, the cool shot will not have staying power as a ridge of high pressure builds overhead later in the week and opens the door for warmth to surge northward.
An uptick in humidity will also accompany the building warmth later this week, especially across the Midwest.
At the same time, AccuWeather.com meteorologists will be watching a developing area of low pressure off the Southeast U.S. coast. The system could become the first tropical feature of the season.
High temperatures later this week will either be near or above highs recorded early this week in most of the Midwest and Northeast. Winds flowing in from the ocean could limit or slow the warming along the mid-Atlantic coast and eastern New England, including in Boston.
For those planning to take advantage of the warmth to plant flower beds, gardens and crops, AccuWeather.com Meteorologist Mark Paquette states, "I anticipate that the I-95 corridor, Ohio Valley and places near the shores of the Great Lakes are out of the woods for a frost."
"The period from May 13-15 may produce a clear, calm and cool night that could bring the last frost threat of the season for the Upper Midwest, northern Pennsylvania, upstate and western New York and the interior of New England," he added.
The warm days this week in the Northeast will serve as a preview of the "periods of warmer-than-normal temperatures that will come and go during the course of the summer," AccuWeather.com Expert Long-Range Forecaster Paul Pastelok expects.