Low temperatures Monday and Tuesday nights could break records, forecasters say. If the area hits 100 degrees, it will be only the 20th time it’s been recorded since 1922, according to data from the National Weather Service. Here is a list of Allentown’s triple digit days in the last 103 years.

Extreme humidity and heat will affect about 265 million people across the country this week. Maps show where and when to expect the worst.