The summer of 2025 brought unprecedented flash flooding across the U.S., with the central and eastern regions hit particularly hard. These storms claimed hundreds of lives across Texas, Kentucky and several other states and caused widespread destruction.
At the same time, every hurricane that formed, including the three powerful Category 5 storms, steered clear of the U.S. mainland.
Both scenarios were unusual -- and they were largely directed by the polar jet stream.
What is a jet stream?
Jet streams are narrow bands of high-speed winds in the upper troposphere, around four to eight miles (seven to 13 kilometers) above the surface of the Earth, flowing west to east around the entire planet. They form where strong temperature contrasts exist.
