METAR, TAF and the time that matters

Start with three different clocks

Before interpreting a weather report, identify the station, when the report was issued, and the period it describes. A METAR is an observation; a TAF describes expected conditions during a stated forecast period. The time you downloaded either one is not the time the weather occurred. AWC explains the report groups and UTC time notation in its aviation weather data guide.

A fictional METAR, decoded

Training example only — invented weather, not a current report: METAR KLIT 220955Z 18010KT 10SM SCT040 20/10 A3000.

• KLIT: the reporting station, Little Rock. 220955Z: observation on the 22nd at 09:55 UTC; the group alone does not state month or year.
• 18010KT: wind from 180 degrees true at 10 knots. This is where the wind comes from, not where it is going.
• 10SM: reported visibility of 10 statute miles, not nautical miles.
• SCT040: scattered clouds with a base 4,000 feet above the ground, not an MSL altitude. 20/10: temperature/dew point in Celsius. A3000: altimeter setting 30.00 inches of mercury.

Compare the groups with the NWS decoding guide and its METAR explanation. This example demonstrates notation; it does not establish that a flight is suitable or describe conditions along a route.

A practical reading order

1. Place and time: confirm the airport identifier and report time. Check that the TAF covers your intended arrival, including reasonable delay.
2. Conditions: read wind, visibility, weather, sky conditions and relevant remarks together. Do not stop after a favorable wind value.
3. Change: find the forecast groups that overlap departure, arrival and possible later arrival. Read changes rather than treating the first group as the whole forecast.
4. Context: compare surrounding observations and the route-wide weather picture. A terminal forecast is not a forecast for your entire route.

The AWC Terminal Weather Dashboard can place earlier observations alongside the forecast timeline. This makes it easier to ask whether conditions are evolving as expected, without treating a color category as a complete briefing.

Make a small briefing note

Use four headings: departure, route, arrival and other options. Under each, record the product time and the question it answers. For example: “Will the arrival forecast still apply if departure slips?” is more useful than copying an unexplained green airport symbol. Write down anything you need clarified by an instructor or briefing specialist.

The common trap

A fresh screen can contain an old report, and a current observation does not promise the same conditions at arrival. Missing data also means missing information, not favorable weather. If reports disagree or a station is unavailable, investigate the gap rather than averaging it away.

Use this reading workflow to organize a current briefing. It is not a complete decoding course or an authorization to fly in the conditions shown.