(CNN) — Anyone who’s drinking hot pumpkin spice lattes in a chunky sweater may need to rein it in for a little while. The crisp weather many in the United States enjoyed over the last week or two was just a sneak peek of fall: Late summer heat is making a comeback.

Temperatures will start getting toasty Friday, and by Sunday, over 90 million people in the central and eastern US are expected to have afternoon highs above 90 degrees Fahrenheit.

The jet stream will lift all the way into Canada this weekend across the eastern half of North America. When the jet soars north, it opens the gate for warm air to travel well beyond its usual early-September stomping grounds.

Technically, it’s still astronomical summer until the autumnal equinox on September 22, so the season’s second wind isn’t

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