SIGMETs

What Are SIGMETs?

SIGMET stands for Significant Meteorological Information. These are formal weather warnings issued to alert pilots and aviation operators to hazardous weather conditions that could pose a risk to aircraft in flight. The Met Office, as the designated Met Watch Office for the UK, is responsible for issuing SIGMETs for the UK Flight Information Region (FIR).

SIGMETs are issued for phenomena such as:

• Thunderstorms
• Severe turbulence
• Severe icing
• Volcanic ash
• Tropical cyclones
• Widespread smoke events, such as the one experienced in October 2017 

These alerts are designed to support flight safety by ensuring that pilots are aware of significant weather hazards along their route or within their area of operation.

Click here to find out more about our provision of Smoke SIGMETs. 

Who Are They For?

• Commercial and General Aviation Pilots – To avoid hazardous weather en route.
• Air Traffic Controllers – To manage airspace and reroute aircraft as needed.
• Flight Operations Teams – To support decision-making and risk management.

What Do They Include?

• Type of hazard (e.g. turbulence, icing, smoke)
• Location and altitude range affected
• Time of onset and expected duration
• Movement and intensity of the weather phenomenon

SIGMETs are concise, coded messages that follow international ICAO standards to ensure consistency and clarity worldwide.

When and How Are They Issued?

• Issued as needed, whenever hazardous weather is observed or forecast.
• Updated as conditions evolve, or new hazards are identified.

How Can I Access the Service?

SIGMETs for the UK FIR can be accessed via the Met Office’s Aviation Briefing Service