An intense and prolonged heat wave is expected to grip parts of the central and eastern United States ahead of Independence Day celebrations, with temperatures climbing into the 90s and 100s and humidity pushing heat index values well above 100 degrees.

Cities including Chicago, Minneapolis, Kansas City, St. Louis, Memphis, Nashville, Savannah and Philadelphia are among those under alerts, with some expected to remain in effect through Thursday. High temperatures will generally climb into the 90s and 100, but humidity will make it feel even hotter, with heat index values reaching 105 to 110 degrees in some areas each afternoon.

The heat will build through the week in the East. Philadelphia, Washington and New York could see heat index value surge past 100 by midweek, with Philadelphia feeling as hot as 112 degrees by Thursday and New York nearing 108.

Much of the Southwest was already facing highs of around 100 degrees. Across the Atlantic, a historic heat wave sweeping Europe has turned deadly. French officials said the country recorded about 1,000 excess deaths during the recent stretch of record-breaking heat.