Why overnight temperatures make U.S. heat wave even more excruciating

Brutal heat wave grips U.S.

A brutal heat wave will scorch more than half of the country this weekend. About 195 million people will be broiling in 90 degree temperatures or higher over the next 24 to 48 hours. Parts of the upper Midwest and along the East Coast facing temperatures that feel like 110 degrees. The National Weather Service says about 120 record-high minimum temperatures could be set – meaning there will barely be any relief at night.

Temperatures in many cities may struggle to drop below 80 at night, which allows the heat to build at an even faster pace the next day, reports CBS News' Kris Van Cleave from New York City. With the added humidity Friday, it's expected to feel somewhere up to 104 degrees in New York but Saturday and Sunday it will be feeling around 110.

How to spot and prevent heat-related illnesses

Normally beaches are packed over the summer but people are being warned to avoid extended periods in the sun. That warning extends into several cities, including Philadelphia and New York where city officials ordered emergency declarations through the weekend.

In New York, the annual triathlon scheduled for this Sunday has been canceled due to the extreme heat. The more than 3000 athletes will receive a full refund. Race officials say they were unable to provide a "safe event experience". 

In upstate New York, Saratoga Race Track has canceled all of Saturday's races.

A tip if you're still planning to look for some relief at the beach: be mindful of potentially dangerously hot sand: Sand absorbs heat at a fast rate and warms up much faster than water. So on hot days like this weekend it can cause serious burns if you aren't careful.