NEW YORK (Dow Jones)–The summer’s heat came a little early this year for large parts of the U.S. stretching from the southwest to the northeast, causing demand and prices for electricity prices to pop higher.

Typically temperatures tend to peak in July and August, but this week they have already hit record levels for this time of the year in places like Houston, Minneapolis and Philadelphia.

“It’s certainly an extreme weather pattern,” said meteorologist Dave Houk. “From Texas, Oklahoma, Kansas up to Arkansas, the big heat has been the most persistent and it comes in waves across the northern …

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