At least 130 million people from Texas to Maine are under alert for dangerous heat and humidity over the next few days.

Hot and sticky temperatures will make it feel as high as 115 degrees in parts of the Mississippi River Valley. Even Niagara Falls will get no relief from the sweltering conditions; the tourist destination will feel like the mid-to-upper 90s on Thursday.

The heat index in Chicago, which factors in humidity, will make it feel in the triple digits and nighttime and early-morning temperatures will provide little comfort. As of 4 a.m. Thursday, the actual temperature was 80 degrees, or 85 with the heat index.

Texas will be just as hot on Thursday, as the heat index is expected to make it feel 107. Up north in Detroit, it’s forecast to feel 102.

Dangerous heat will spread to the Mid-Atlantic and Northeast as temperatures in the I-95 corridor from Washington, D.C., to Portland, Maine, will make it feel like it’s in the mid-90s on Thursday.

Maine is under a heat advisory mainly for Friday as the heat index will make Portland, Maine, feel like it’s 100 degrees.

New York City, Boston and Philadelphia are also bracing for extreme temperatures. On Friday, the feels-like temperature is expected to be reach 104 in New York City, 103 in Boston, 106 in Philadelphia and 109 in Washington, D.C., and Baltimore.

Meanwhile, the Midwest and the Southeast is expected to see hot and humid weather stretch into the weekend and into early next, as the heat indices are expected to make it feel 110 degrees in some parts.

Most of the Southeast, including Atlanta, is expected to see a level four out four “extreme heat risk” on Monday and Tuesday as a potentially life-threatening heat wave continues in the region.

Besides the heat, the Midwest, specifically Kansas and Missouri, is expected to see a summer flash flooding continue. Strong thunderstorms on Thursday could cause flooding across the region, which is still recovering from flash floods earlier this week.

Heavy thunderstorms are expected to develop over the Midwest on Thursday afternoon and through the night, with rainfall totals forecast to reach 2 to 4 inches or higher in some areas along the I-70 corridor. The Kansas City region may see the brunt of storms with multiple rounds of heavy rain possible.