Dangerous heat wave impacting large swathes of the U.S. this week, forecasters warn
A long and dangerous heat wave will blast a large swath of the United States this week, the National Weather Service said, with temperatures rising ahead of the July Fourth holiday and feeling even hotter because of the high humidity that's arriving with it.
More than 100 record-high temperatures are expected through Saturday night, including in major cities like New York City and Washington, D.C., which are expected to see record highs into the 100s, according to CBS News meteorologist Nikki Nolan.
Philadelphia, Baltimore and Midwestern and Great Lakes cities including Chicago, St. Louis and Detroit are also expected to feel the heat. Southern cities including Dallas, Little Rock, Arkansas, and Memphis, Tennessee, will also see high temperatures.
More than 250 record-warm overnight lows are expected through Saturday night.
High heat will last into next weekend across the Great Plains, the Southeast and the Mid-Atlantic, according to forecasters.
It's the first widespread heat wave of the summer, impacting more than half of the country. The heat wave is expanding across the central and eastern U.S., while the Four Corners remain under dangerous fire weather conditions. At the same time, severe thunderstorms continue across the northern Plains and Upper Midwest, with flooding concerns stretching from the Rockies into the Mid-Atlantic.
As temperatures climb, high humidity will lead to heat indices of 100 to 110 degrees F (40 C to 43 C), and as high as 115 F (46 C), according to the weather service. Nightly lows in the 70s F (21 to 26 C) won't provide much relief.
The heat index, which factors in humidity and is included on many weather forecasts, provides a sense of how hot it really feels — and what's dangerous for prolonged exposure or strenuous activity.
Parts of the U.S., especially Phoenix, Las Vegas, central Texas, and much of the Southwest, were already experiencing temperatures around 100 F.
During extreme temperatures, people are advised to limit outdoor activity, stay hydrated and ensure access to air-conditioning and other cooling areas, the weather service said. The Centers for Disease Control and Prevention says heat can impact anyone. Signs of overheating include muscle cramping, dizziness, unusually heavy sweating, shortness of breath, headaches, weakness and nausea.
The heat comes after Europe has been sizzling for days, with Germany seeing record-high temperatures over the weekend. Switzerland, the Czech Republic, Denmark and France have also been facing high temperatures. In France, dozens of drowning deaths were recorded this month as swimmers turned to the water for relief from the heat.
