Relief is near. But you're still probably going to want to stay inside.

The deadly heat wave that had millions of people from the Midwest to the East Coast searching for any way to cool down will be ushered out by showers and thunderstorms, which began Sunday night and could bring excessive rainfall, according to the National Weather Service.

The storms will be slow-moving, increasing the chance for flash flooding, the weather service warned. The upside is that the storms will bring "a much-appreciated cooler air mass," with temperatures of about 10 degrees below average east of the Rockies, where residents suffered through a weekend of record-breaking high temperatures and staggering humidity.

Here is a look at the high temperatures observed across the Eastern US this weekend. Several locations across the mid Atlantic reached the 100 degree mark on Sunday, with several more locations falling just a degree short. pic.twitter.com/w7qQdMz2bw — NWS Eastern Region (@NWSEastern) July 21, 2019

Sunday evening thunderstorms in New Jersey knocked down trees, power lines and a construction crane that crashed into a home with a woman inside who was not injured, according to NBC New York.

In Bethlehem, Pennsylvania, a child between the ages of 5 and 6 was struck by lightning Sunday night as a storm moved in, according to NBC Philadelphia. The condition of the child who was hospitalized was not known Monday morning.

Residents in Michigan and Wisconsin lost power due to the storms, and officials in the Northeast warned that high winds and heavy rainfall could cut power throughout Monday.

In New York, almost 60,000 customers had to endure the heat without air conditioning after losing power Sunday night. About 19,000 customers in the state, including 13,000 in Brooklyn, were still without power Monday morning, Mayor Bill de Blasio said. Utility company Con Edison said power should be restored by the afternoon.

Con Edison had intentionally cut power to about half of the customers affected by the outage. De Blasio on Monday called for a "full investigation" into the situation, adding that the outages were avoidable and the company has provided "no answers whatsoever as to why this happened."

He had urged residents over the weekend to turn off unnecessary appliances so as not to overwhelm the grid. "Please everybody, this is serious, serious stuff — the hottest its been in many many years," he said.

***Attention New York City***



Sunday has been canceled. Stay indoors, nothing to see here. Really, we got this.



And if you see our officers working out there today in the heat wave, a smile and a Thank You will go a long way (but maybe no hugs.) #SundayMotivation pic.twitter.com/KJjpoUdtuN — NYPD NEWS (@NYPDnews) July 21, 2019

Record temperatures were recorded Saturday at New York City's John F. Kennedy International Airport and at Atlantic City, New Jersey, with 99 degrees registered in each location.

Both Boston and Hartford, Connecticut, came within two degrees of their record highs for the date, at 97 and 98 degrees, respectively.

But the figures did not reflect how hot it felt because humidity boosted perceived temperatures into the triple digits, forecasters said, making New York City feel like 111 degrees, Washington 112 and Chicago 105.

The deaths of two people in Maryland and two people in Illinois have been blamed on the severe heat since last week. And former N.Y. Giants player Mitch Petrus, 32, died from heatstroke in Arkansas, officials said Friday.