Temperatures are forecast to reach the 90s and 100s on Thursday for the East Coast and Southern Plains.
CNN  — 

Nearly 80 million people, primarily in cities along the East Coast, are under heat advisories on Thursday, including residents of Boston, New York, Philadelphia and Washington, DC, as drought conditions worsen in the region.

More than 70% of the US population will experience temperatures at or above 90 degrees over the next seven days, including the East Coast and the South.

The United States has coped with oppressive heat the past few weeks. As of yesterday, eight out of the last 16 days had witnessed 100 million or more Americans under heat alerts.

Thursday heat alerts include the Northeast and Great Plains.

Temperatures will be 10 to 15 degrees above normal across the Northeast and New England, where it will feel like the upper 90s and 100s this afternoon. High temperatures could break records in over a dozen locations. Farther south, the Mid-Atlantic coast will feel like up to 107 degrees.

Above-average temperatures over the past week, combined with sparse rainfall, contributed to flash drought conditions in the Northeast.

The latest US Drought Monitor released Thursday morning shows moderate and severe drought expansion in the New York City area and parts of New England.

“Short-term moderate and severe drought continued to expand, especially in the New York City area, New Jersey, and New England, where rainfall was sparse and temperatures were a few degrees above normal,” the drought monitor said.

Friday will be slightly cooler for the Northeast, but temperatures in the Plains heat up.

After a hot day Thursday, a cold front approaching from the Midwest will cool down the Northeast by Friday. The region will see increased cloud cover and storm chances going into Friday, allowing temperatures to come down slightly. Humidity will remain high as temperatures become more seasonable on Saturday, allowing it to continue to feel like the upper 90s across much of the Northeast and Mid-Atlantic.

Temperatures will remain in the 90s for most of the East Coast on Saturday.

Eastern Kentucky, where floods ravaged the area last week, will contend with high heat and humidity again on Thursday. It will feel like 95 to 100 degrees, causing concern for those still without power and working outside. Isolated thunderstorms return to the forecast this afternoon, with a greater likelihood of storms Friday and Saturday, lowering the heat threat the next two days.

The Southern Plains – also under heat advisories - will continue its streak of hot weather today, with temperatures above 100 and feeling even hotter.

Drought also continued to expand in some areas of the Southern Plains, where temperatures continue to be above average. That’s especially true in Texas, where there were many readings of 4 to 8 degrees above normal. Dallas has been very familiar with heat advisories recently and has reached 100 degrees every day since July 15.

Across the Northern Plains and into the Midwest, temperatures will increase into the 90s and 100s as the bubble of high pressure stationed over the central US lifts north on Friday.