What is the typical duration of a SIGMET for severe weather?

A SIGMET, or Significant Meteorological Information, is a weather advisory that informs pilots about significant weather conditions that may impact flight safety, such as severe turbulence, icing, or thunderstorms. The typical duration of a SIGMET for severe weather is indeed 4 hours.

This duration is established to ensure that the information provided remains relevant and timely for flights in the affected area. If severe weather conditions persist beyond this time frame, the SIGMET can be reissued based on updated assessments from meteorological authorities. The 4-hour duration strikes a balance between providing adequate lead time for pilots to adjust their flight plans in response to evolving weather situations while ensuring that the information remains pertinent.