July will make a potentially record-breaking exit this week as a heat dome will create triple-digit feels-like temperatures for millions from Florida to Virginia, prompting heat alerts across the East Coast.

A heat dome​ is trapping over 90 million Americans in extreme temperatures this week with the National Weather Service​ issuing heat alerts from Nebraska to Florida.

In the beginning, a heat dome evaporates moisture in the soil. But then, the evaporation will significantly raise humidity.

The Florida Peninsula and the western tip of the Panhandle could see heat index values between 105 to 110 degrees, which may end up being conservative estimates. High temperatures in Santa Rosa County are currently forecast to hit triple digits starting on Monday. Escambia County highs aren’t far behind them.

Tropical activity is picking up in both the Pacific and Atlantic basins as a massive heat dome sends temperatures soaring across the U.S.

Much of July‘s seemingly intractable hot weather is being fueled by a “heat dome” that has been lingering in the eastern United States for about a month. These slow-moving, high-pressure systems are a weather phenomenon in which a section of high pressure over an area traps heat and humidity for an extended period of time.

First Alert Weather Days have been declared for today through Wednesday with a dangerous heat dome building across Alabama and bringing the hottest days we have seen thus far this summer.

The blast of heat prompted advisories across much of Massachusetts, Rhode Island, Connecticut, and in Southern New Hampshire and Maine.