Definition
A weather advisory issued by the National Weather Service concerning weather phenomena that are potentially hazardous to all aircraft, regardless of size or type. SIGMETs cover conditions such as severe or extreme turbulence, severe icing not associated with thunderstorms, and widespread dust storms, sandstorms, or volcanic ash that reduce visibility to less than three miles.
Plain English
An official weather alert warning pilots about dangerous weather that could affect any aircraft flying through it, not just small planes.
Context Anchor
You may see SIGMET Information during a preflight weather briefing, in aviation weather products, or when checking conditions along a planned route.
Derivation
SIGMET combines 'SIG' from significant and 'MET' from meteorological. The name signals the intent: this is weather information serious enough that every pilot needs to know about it.
Why Pilots Care
Pilots use SIGMET Information to change routes, delay flights, or prepare for hazards that could lead to loss of control or damage to the aircraft.
Intuition Check
Do not read “Information” as casual background information. SIGMET Information is an official safety advisory about serious weather that may affect all aircraft.
Example Sentence 1
Before departure, the pilot reviewed an active SIGMET for severe turbulence along the planned route and chose a lower altitude to avoid it.
Example Sentence 2
While airborne, the crew received updated SIGMET Information reporting a line of thunderstorms moving across their planned path.