Both TAF and METAR reports are crucial in aviation for weather information, though they serve different purposes. While a TAF is basically a forecast of the expected weather patterns over the next 24 to 30 hours, a METAR provides current weather observations at a specific airport. Planning and making the right decisions about flights depend on how to interpret a TAF and the differences between these reports.
What is METAR?
METAR, or Meteorological Aerodrome Report, is a real, current-weather observation at an airport. These usually change hourly, but more frequent reports are issued when conditions change rapidly. The METAR includes temperature, cloud cover, visibility, wind direction, and speed. In many ways, the METAR is a brief description of the weather that might impact current activities, such as landing and departure.
What is a Terminal Aerodrome Forecast?
A TAF, on the other hand, or Terminal Aerodrome Forecast, is simply a forecast of what should be expected regarding weather at a certain airport for a certain period. The forecast updates every six hours and covers 24 to 30 hours, depending on the needs of each airport. Where a METAR describes what the current weather is, a TAF lets the pilots know what the weather will be. This makes it very important in planning and preparation when guessing future conditions.
Key Differences Between TAF and METAR
- Purpose
METAR: Provides real-time, current weather observations.
TAF: Offers a forecast, giving an outlook on weather conditions over the next day or more
- Update Frequency
METAR: Updated every hour, with special reports (SPECI) if weather changes suddenly.
TAF: Updated every six hours, providing extended forecasts for aviation.
- Coverage
METAR: Generally applies to current conditions within a specific area around the airport.
TAF: Covers expected conditions within a roughly 5-mile radius of the airport.
- Coding Format
While both use similar weather codes, TAFs may include “FM” (from), “TEMPO” (temporary), and “PROB” (probability) to denote changes within the forecast period. METARs lack these forecast-specific modifiers since they reflect actual conditions.
How to Read a TAF
Although TAFs may seem complicated at first, it is helpful to break them down into smaller components. This is an illustration of a TAF and how to read it:
Here is an example reading a TAF:
TAF KATL 241730Z 2418/2524 27010KT P6SM SCT020 BKN040
FM250100 24012KT 5SM -SHRA OVC020
TEMPO 2503/2505 3SM TSRA BKN015
- TAF KATL: This report is for Atlanta International Airport.
- 241730Z: Issued on the 24th at 17:30 UTC.
- 2418/2524: Valid from the 24th at 18:00 UTC to the 25th at 24:00 UTC.
- 27010KT: Winds from 270 degrees at 10 knots.
- P6SM: Visibility greater than 6 statute miles.
- SCT020 BKN040: Scattered clouds at 2,000 feet, broken clouds at 4,000 feet.
Later, from 01:00 UTC, a shift occurs:
- 24012KT: Winds change to 240 degrees at 12 knots.
- 5SM -SHRA OVC020: Light rain showers reduce visibility to 5 statute miles, with overcast clouds at 2,000 feet.
The “TEMPO” line indicates that temporarily, between 03:00 and 05:00 UTC on the 25th, thunderstorms (TSRA) may reduce visibility to 3 statute miles with broken clouds at 1,500 feet. You can find more examples in IVAO’s Documentation Library.
Why TAF and METAR Matter Together
On the other hand, a Terminal Aerodrome Forecast (TAF) forecasts the weather that is likely to occur at a particular airport over a predetermined time frame. Depending on the needs of the airport, TAFs typically cover 24 to 30 hours and are updated every six hours. A TAF provides information on the weather that is anticipated, which is crucial for planning and predicting future circumstances, whereas a METAR informs pilots of the current meteorological conditions.
Learn more about airport signs and markings in one of our previous articles!
