How long is a non-convective SIGMET valid for?

A non-convective SIGMET is valid for 4 hours. This duration is established to ensure that pilots and meteorologists are informed of significant weather phenomena that can impact flight operations, such as volcanic ash, dust storms, or other severe weather that is not related to thunderstorms. The 4-hour validity period allows for updates to be issued as conditions change, providing essential information for planning and safety.

The choice of 4 hours strikes a balance between being timely and allowing enough time for those in the aviation community to take necessary precautions or route adjustments. Following this timeframe, new SIGMETs can be issued to reflect current conditions and ensure that the information pilots are using is as accurate and relevant as possible.