Low-level jets are wind maxima that frequently occur at wind turbine rotor heights. This work investigated their properties and their impact on wind turbines using 3 years of wind measurements in Dunkerque, a coastal city in the North Sea. Results showed that jets are frequent (15 % of the time), could decrease current turbines' production, and could expose them to unfavorable structural conditions, whereas future turbines will be less impacted and will see an increase in energy production.