WASHINGTON — A scorching heatwave searing the United States was expected to begin to ease slightly Sunday, but authorities warned that temperatures will still remain high and dangerous through most of the weekend.

The heatwave was responsible for at least 36 weather-related deaths in various parts of the country, The New York Times reported.

Temperatures as high as 99 degrees Fahrenheit (37.2 Celsius) were forecast for the Washington metropolitan area for Sunday, a notch cooler than the 105 degrees (40.5 Celsius) recorded on Saturday, but still very hot and dangerous, especially for the elderly and people with heart conditions.

Heat measured by 105 degrees was registered also in Kansas City, Kansas, and Louisville, Kentucky. Even way up north, in Sioux Falls, South Dakota, the thermometer rose to 104 as it did in Indianapolis, Indiana. In Baltimore, Maryland, it reached 102 degrees and in Philadelphia, Pennsylvania, 101.

However, blistering temperatures were expected to cool "significantly" by Monday as a cold front pushed south from Canada to the central and eastern United States, the National Weather Service said.

The breather will likely be accompanied by fierce storms, forecasters warned, possibly spelling disaster for states still recovering from a killer band of thunderstorms that wreaked havoc last week, leaving millions without air conditioning or refrigeration after power cuts.

"Severe weather, including damaging wind, is expected to accompany this cold front," the weather service said, adding later that hail and isolated tornadoes could not be ruled out.

A week after the devastating June 29 thunderstorms, 416,192 customers in West Virginia, Virginia, Ohio, New Jersey, Maryland and Indiana were still off the power grid -- down from several million -- according to the latest Energy Department update issued Friday.

Ten deaths are tied to the heatwave in Chicago, Illinois, with the neighboring state of Wisconsin reporting at least three fatalities, local media reported.

In Ohio, where another three deaths are being blamed on the weather, the health department urged citizens to check up on each other.

"Ohioans are in this heatwave together!" it said on its website.

"Reach out and make sure those around you -- neighbors, family, church members or customers in your business -- have the tools they need to stay healthy and be safe."

With temperatures still soaring as the weekend kicked off, authorities urged caution to avoid heat-related health problems.

In Chicago, where the mercury has hit 100 degrees Fahrenheit (38 Celsius) for the past three days, an extreme heat warning that had been set to expire Friday evening was extended until late Saturday, the Chicago Tribune reported.

Hours at public swimming pools in the capital Washington meanwhile were expanded to provide refuge for people trying to stay cool as temperatures hit their peak on Saturday.

Just minutes from the White House, 35-year-old Sarah Washington and her eight-year-old daughter Raquia sold cold water bottles in an effort to raise money for neighbors hit by recent storm-related power outages.

"We're just trying to help a few families," said Washington as she sought shelter from the sun at a bus stop.

Record-breaking temperatures have lasted several weeks. Over the past 30 days, more than 4,500 daily record highs have been recorded around the country, according to CNN.

Meteorologists blame the sweltering weather on a huge heat dome over large swathes of the country. High-pressure air in the domes blocks cooling winds, setting hot temperatures, higher humidity and very little breeze underneath.

Coupled with a drought in certain areas, the blistering heat has also taken a toll on US farmland.

"In the primary growing states for corn and soybeans, 22 percent of the crop is in poor or very poor condition, as are 43 percent of the nation's pastures and rangelands and 24 percent of the sorghum crop," the US Drought Monitor said in its latest update issued earlier this week.