METAR and TAF Decoding Practice for DGCA Meteorology

Every DGCA Meteorology paper has at least one question that hands you a raw METAR or TAF string and asks you to pick out the wind, the visibility, or what a change group means. Most candidates lose these marks not because the concept is hard but because they never actually sat down and decoded a full string end to end. This guide does that. We go group by group through both report types, then decode three complete strings from Indian airports, then give you one to decode yourself with the full answer laid out afterward.

Report structure: what METAR and TAF actually are

A METAR (Meteorological Aerodrome Report) is a snapshot. It tells you what the weather was doing at the aerodrome at the exact time it was observed, and it is issued routinely every 30 minutes at most international Indian airports, hourly at smaller ones. A SPECI is the same format issued outside the routine schedule when conditions change sharply enough to warrant it.

A TAF (Terminal Aerodrome Forecast) is a prediction. It covers a stated period ahead, usually 24 hours at Indian domestic aerodromes and 30 hours at major international ones, and it uses a small set of change indicators to show how the forecaster expects conditions to shift within that window. Both formats use the same building blocks for wind, visibility, weather and cloud, so once you can read a METAR, a TAF is mostly the same skill plus the change groups layered on top.

METAR groups explained

Read a METAR left to right. Each group has a fixed shape, and once you recognise the shape you can identify a group even if you have never seen that particular airport's report before.

A few sub points examiners like to test. Wind direction is always given in degrees true in the coded group, not magnetic, though ATC gives it to you in magnetic verbally. Calm wind is coded 00000KT. A variable direction at low speed is shown as VRB, for example VRB02KT. When the wind direction varies by 60 degrees or more either side of the mean during the 10 minutes before observation, and the mean speed exceeds 3 knots, a variability group like 240V300 is appended after the main wind group.

Visibility below 800 metres steps in 50 metre increments, from 800 up to 5000 metres it steps in 100 metre increments, and above 5000 up to 9999 it uses whole kilometre steps written as thousands of metres. 9999 means visibility of 10 kilometres or more. If visibility differs markedly by direction, a minimum visibility with its compass direction is added as a second group.

Weather phenomena codes combine three optional parts: intensity (- for light, no sign for moderate, + for heavy), a descriptor (MI shallow, BC patches, DR drifting, BL blowing, SH shower, TS thunderstorm, FZ freezing), and the phenomenon itself (RA rain, DZ drizzle, SN snow, BR mist, FG fog, HZ haze, DU dust, SQ squall, FC funnel cloud, GR hail). TS alone with no phenomenon following it is not valid; it is always paired, for example TSRA for thunderstorm with rain.

TAF groups explained

A TAF opens the same way as a METAR: station identifier, then an origin date/time group, then the validity period written as two pairs of day/hour, for example 1206/1306 meaning valid from the 12th at 0600Z to the 13th at 0600Z. After that comes a baseline forecast built from the same wind, visibility, weather and cloud groups as a METAR, followed by however many change groups the forecaster needs.

The distinction examiners most often probe is BECMG versus TEMPO. BECMG describes a lasting shift, the new state is expected to hold once the transition window ends. TEMPO describes a fluctuation, the underlying forecast is still valid and the temporary condition comes and goes within the window without permanently replacing it.

Worked example: VIDP METAR

METAR VIDP 121030Z 00000KT 0500 R28/0600N FG VV002 18/17 Q1015 NOSIG RMK FOG DENSE

Worked example: VABB METAR

METAR VABB 150330Z 22018G30KT 3000 TSRA BKN012CB OVC025 26/25 Q1004 BECMG TL0430 5000 SHRA

Worked example: VOBL TAF

TAF VOBL 121700Z 1218/1318 20010KT 6000 SCT018 BKN030
BECMG 1220/1222 21015KT 4000 SHRA BKN015
TEMPO 1300/1306 3000 TSRA BKN010CB
PROB30 TEMPO 1306/1310 0800 FG VV003

Decode this yourself

Read the string below and try to build the full decode before you look at the answer underneath. Cover the answer with your hand or a piece of paper first if you want an honest attempt.

METAR VOHS 090900Z 31006KT 280V340 8000 NSC 24/19 Q1012 NOSIG

Exam tips for METAR/TAF questions

• Work left to right and name each group type before you try to read its value. Half the marks lost are from misreading which group you are looking at, not from misreading the value itself.
• Memorise the visibility step rules (50m below 800m, 100m up to 5000m, whole km above) since examiners like to test edge cases around these boundaries.
• Do not confuse BECMG with TEMPO. If the question describes a lasting shift, it is BECMG. If it describes something that comes and goes, it is TEMPO.
• CAVOK is a complete replacement for visibility, weather and cloud together. If any one of its three conditions fails, CAVOK cannot be used and the groups must be written out individually.
• RVR is reported per runway and only when visibility or RVR itself is below a threshold value, so its presence in a string is itself a clue that visibility is degraded.

FAQ

AviationGrade editorial team

From WMO code FM-15 METAR, FM-51 TAF and ICAO Annex 3

We build the DGCA question banks these guides link to. Corrections welcome and credited.