Temperatures this weekend could drop more than 30 degrees below normal in many spots, especially in the South and East. The period from last weekend into next week could end up being the longest freezing stretch in Philadelphia in nearly 65 years. Farther down the Interstate-95 corridor, it could be the longest freezing stretch in Washington, DC, in more than three decades. That would be the longest stretch since a 10-day cold blast in December 1989. And Chicago — no stranger to freezing weather — is impressively on track to hit an even colder mark: its longest stretch of temperatures below 20 degrees since 2018.