Temperatures will climb to between 90 and 100 F for a two- to four-day stretch in the northeastern United States during the first part of the week, prior to a cooldown.
High-temperature records dating back as far as the 1970s and 1980s will be challenged during the swelter.
The Northeast heat will be a brief eastward extension of a long-duration heat wave for much of the central U.S.
Second heat wave of the year to pack a punch
For many areas of the mid-Atlantic and southern New England, this will be the second heat wave of the year, following three days in a row of 90-degree temperatures during the middle of May. In much of this region, the heat wave will span Sunday through Tuesday.
In northern and eastern New England, temperatures reaching or exceeding 90 will be limited to two days, Sunday and Monday. But for many parts of Maine and northern New Hampshire, this will be the longest stretch of 90-degree weather of the year so far.
No matter what the official designation, the surge in heat and humidity will hit like a sledgehammer, when combined with intense June sunshine and relative to most days in the past several weeks.
While humidity levels will not be as high as some heat waves of the past during July and August, they will be higher than what many people are used to.
AccuWeather RealFeel® Temperatures will reach dangerous levels for several hours during the afternoons.
Over the next few weeks, the sun is at its highest point in the sky and can easily make 90-degree temperatures feel like 100 to 105 and 95-degree temperatures in urban areas feel like 105 to 110.
People should limit strenuous physical activity during a weather pattern such as this. If you must exercise or do manual labor try to do so in the early morning or evening hours.
The sunshine and heat will give area crops a needed boost, following cool conditions that have been inhibiting growth.
The weather will offer opportunities to enjoy the pool and spend time on the beach.
People venturing into area lakes, streams and the ocean should be aware that waters are still chilly this early in the season. Waters are generally in the 60s or lower from Delaware and Maryland on north.
Cold water shock and hypothermia can hit anyone, at any age, no matter how physically fit.
Heat wave to break down during the middle of next week
People who mind the heat or who have limited means to keep cool will only have to hold on for a few days.
"During Tuesday to Thursday, cooler air from eastern Canada will push southward across the northeastern U.S. and will mark the end of the heat wave," according to AccuWeather Meteorologist Evan Duffey.
New England will feel the cooler air first on Tuesday, followed by southeastern New York, New Jersey and Pennsylvania on Wednesday, and then finally Delaware, Maryland, Virginia and West Virginia on Thursday.
"The cool waters of the Atlantic will help to fuel the cool push and are likely to produce a swath of low clouds," according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok.
The most dramatic cooldown will be along the immediate coast of New England, where highs in the middle 90s will be replaced with highs in the middle to upper 60s.
However, temperatures may even stay in the upper 60s for a day in New York City on Thursday following three days of 90-degree temperatures.
Another factor that will contribute to the breakdown of the heat wave in the Northeast will be an influx of moisture from the Gulf of Mexico.
"Even as the cool flow from the Atlantic Ocean eases up, clouds, showers and thunderstorms could mitigate and prevent a rebound of widespread heat in the Northeast late next week and next weekend," Pastelok said.
Highs in the 70s north to 80s south are likely across the region next weekend, instead of highs mainly in the 90s.