Much of the Eastern U.S. experienced a chilly, rainy, unofficial start to summer during Memorial Day weekend, though clearer skies and warmer temperatures are expected Monday. 

"Memorial Day is likely to flip from cloudy and cool to bright and beautiful for the central Appalachians and even much of the mid-Atlantic coast," AccuWeather Chief On-Air Meteorologist Bernie Rayno said, according to reports. 

Record cold temperatures gripped the Northeast due to a "stubborn upper-level low" over southeast Canada that pulled down cooler air and kept the air unsettled, ABC News reported.  

EASTERN US TO FACE SEVERE THUNDERSTORM AND FLOODING THREATS FOR MEMORIAL DAY WEEKEND

NYC saw a high of 51 degrees on Saturday, reports said. Coastal Flood Watches and advisories were in effect from Long Island to the Delmarva Peninsula. 

Fog shrouds lower Manhattan and One World Trade Center in New York City as pigeons stand on a railing in the rain on May 30, 2021, in Jersey City, New Jersey. (Photo by Gary Hershorn/Getty Images)

Most of the rain is expected to push north and east on Monday, reports said. Though conditions in parts of New England are likely to be cloudy, with rain and drizzle, for much of Memorial Day. 

Still, the Atlantic coast from New Jersey to Maryland could experience some sunshine before the holiday weekend is over, according to AccuWeather. 

"While Monday may be the best of the three days over much of the Northeast states, that is not likely to be the case in much of New England and eastern Long Island," AccuWeather Senior Meteorologist Dean DeVore said.

As skies clear in parts of the Northeast, excessive rainfall is projected for portions of the Texas panhandle, and northwest Texas, according to the National Weather Service (NWS).

On Sunday, late afternoon radar imagery showed scattered cells extending from eastern Colorado into northeast New Mexico along with adjacent portions of Kansas southward to the Panhandles and west Texas.

"There continues to be a strong model signal for widespread heavy to locally excessive rainfall amounts from Sunday into early Monday morning stretching from northwest Texas, northward into the Texas/Oklahoma Panhandle and far southwest Kansas," according to the NWS Weather Prediction Center.

The potential for severe weather was expected to increase as storms moved from eastern New Mexico into western Texas.

"Large hail and damaging winds are the main threats with these storms, though a brief tornado cannot be ruled out," the NWS added. 

NATIONAL WEATHER FORECAST: SEVERE STORM THREAT REMAINS WHILE EAST TO COOL OFF OVER MEMORIAL DAY WEEKEND

On the West Coast, there were excessive heat warnings and heat advisories issued across California's interior Sacramento Valley and Northern San Joaquin Valley for Sunday and Monday.

"Over 9 million people in California are currently under a Heat Advisory or Excessive Heat Warning," wrote the NWS Bay Area on Sunday.