Regional‐scale jet waviness modulates the occurrence of midlatitude weather extremes

Abstract Several studies have attributed the occurrence of recent weather extremes to an amplified waviness of the upper tropospheric jet stream. Although trends in jet waviness are still under discussion, it is crucial to better understand the mechanisms through which jet waviness affects weather extremes. Here we show that variations in jet waviness on regional scales effectively modulate the occurrence of daily weather extremes but in regionally different ways. The jet waviness over the North Atlantic and the North Pacific mainly affects where wind, precipitation and cold extremes occur, while a wavy jet over Eurasia strongly favors the occurrence of hot extremes in summer. This is because regional variations of jet waviness are intrinsically linked to the occurrence and tracks of synoptic‐scale weather systems, which can trigger the extremes. We conclude that potential jet waviness changes would affect the occurrence of weather extremes differently depending on where these changes occur.