Upper Air Forecasts

What Are Upper Air Forecasts and SIGWX Charts?

The Met Office is one of two World Area Forecast Centres (WAFCs) designated by the International Civil Aviation Organization (ICAO). WAFC London, operated by the Met Office, provides global upper air forecasts used by commercial airlines and other high-altitude aviation sectors, such as business jets.

These forecasts include:

• Wind and temperature data at cruising altitudes
• Significant weather (SIGWX) charts, which highlight en-route hazards such as:
  • Jet streams
  • Turbulence
  • Icing
  • Cumulonimbus clouds
  • Volcanic ash
  • Tropical cyclones

This information is vital for flight planning, route optimisation, and in-flight safety.

Who Are They For?

• Commercial Airline Pilots and Dispatchers – For route planning and fuel efficiency.
• Business Jet Operators – To assess upper-level weather risks.
• Flight Planning Services – To integrate global weather data into operational systems.

What Do They Include?

• Global wind and temperature forecasts at flight levels
• SIGWX charts showing:
  • Jet streams (winds ≥80 knots)
  • Areas of turbulence and icing
  • Cumulonimbus cloud coverage
  • Volcanic eruptions and tropical cyclones

These forecasts are delivered in both graphical and gridded data formats, suitable for integration into flight planning software

When and How Are They Issued?

• SIGWX charts are issued at multiple time steps (e.g. T+6 to T+48 hours) in 3-hour intervals 
• Forecasts are updated regularly and distributed via the SADIS system and aviation briefing platforms.

How Can I Access the Service?

Upper air forecasts and SIGWX charts are available through the Met Office WAFC portal 
Guidance on interpreting SIGWX charts is available in the official SIGWX Interpretation Guide