Reading a METAR & TAF.

What a METAR is

METAR stands for Meteorological Aerodrome Report. It is a routine, coded observation of the actual weather at an airport at a specific moment. It is not a forecast — it describes what an automated sensor or a human observer measured, usually within the last few minutes.

Routine METARs are issued at fixed intervals — every 30 minutes at busy international airports, every 60 minutes at quieter fields. When conditions change sharply between routine reports, a SPECI (special report) is issued. A SPECI uses exactly the same code as a METAR; the only difference is the trigger.

The code is deliberately terse so it can be transmitted quickly and read the same way by a pilot in Riyadh, a dispatcher in Frankfurt and an automated flight-planning system. The structure is always the same, which is what makes it learnable. Read the fields in order and each one tells you one thing.

The METAR format, field by field

A METAR is a sequence of groups separated by spaces. Here is each group in the order it appears.

Report type

The report begins with METAR or SPECI. Some sources omit it. A correction to a previously issued report carries COR.

Station identifier

The four-letter ICAO location indicator, for example OERK for Riyadh King Khalid International or OEJN for Jeddah King Abdulaziz International. Saudi indicators all begin with OE.

Day and time

Six digits followed by Z, for example 241200Z — the 24th of the month at 1200 UTC. The day is the calendar day; the time is always Zulu (UTC), never local.

Wind

Direction in degrees true (three digits) plus speed plus unit, for example 27015KT — wind from 270° at 15 knots. Gusts add G, so 27015G27KT is 15 knots gusting 27. Variable direction with a low speed shows as VRB03KT; a wind that varies across a wide arc adds a group such as 240V300. Calm wind is 00000KT.

Visibility

Prevailing horizontal visibility in metres, for example 9999 (10 km or more) or 3000 (3 km). 0050 means 50 m. If visibility differs by direction, a minimum visibility group with a compass point may follow. Runway visual range (RVR) groups beginning with R, such as R34L/0600, give the measured range on a specific runway when visibility is low.

Present weather

One or more coded weather phenomena. An intensity prefix of - (light) or + (heavy) may lead, or VC for "in the vicinity". Then a descriptor and a phenomenon, for example +TSRA (heavy thunderstorm with rain), -DZ (light drizzle), BR (mist), FG (fog), HZ (haze), DU (widespread dust), BLSA (blowing sand). If there is no significant weather, the group is simply absent.

Cloud

One group per significant layer, lowest first: amount plus height in hundreds of feet above aerodrome level. Amounts are FEW (1–2 oktas), SCT (scattered, 3–4), BKN (broken, 5–7) and OVC (overcast, 8). SCT025 is scattered cloud at 2,500 ft. CB (cumulonimbus) or TCU (towering cumulus) is appended when present. NSC means no significant cloud; NCD means an automated station detected no cloud; CAVOK replaces visibility, weather and cloud altogether when conditions are good (see the pitfalls section).

Temperature and dewpoint

Two values in whole degrees Celsius separated by a slash, for example 34/12. A leading M marks a negative value, so M02/M05 is −2 °C over −5 °C. The closer the two numbers, the higher the humidity and the greater the risk of fog or mist forming.

Pressure (QNH)

The altimeter setting. In Saudi Arabia and most of the world it is a Q group in hectopascals, for example Q1013. In regions using inches of mercury it is an A group, for example A2992. Setting QNH makes the altimeter read height above mean sea level.

Recent weather and wind shear

Optional groups. RE marks recent weather that has ended since the last report, such as RERA. WS groups flag reported wind shear, for example WS R16L.

Trend

Some METARs end with a short landing forecast: NOSIG (no significant change expected) or a BECMG / TEMPO trend covering the next two hours.

Remarks

A section starting with RMK holds supplementary, often nationally formatted information. Remarks vary by country and are not standardised the way the body of the report is.

What a TAF is — and how it differs

TAF stands for Terminal Aerodrome Forecast. It is a coded forecast of the expected weather at an airport over a defined period. Where a METAR says "this is what it is", a TAF says "this is what it should become".

The key differences from a METAR:

• It is a forecast, not an observation. It is produced by a forecaster and carries the uncertainty that all forecasts do.
• It covers a period, not a moment. A standard TAF is valid for 24 or 30 hours and is reissued (typically every 6 hours) as the picture changes.
• It is amended. When reality diverges from the forecast, an amended TAF is issued with TAF AMD. A corrected TAF carries TAF COR.
• It uses change groups. Because it spans hours, a TAF needs a way to say "and then conditions will shift". That is what BECMG, TEMPO, FM and PROB do.

Crucially, the weather, wind, visibility and cloud groups inside a TAF are coded identically to those in a METAR. If you can read a METAR wind group you can read a TAF wind group. Only the validity line and the change groups are new.

TAF validity and change groups

A TAF opens with the report type, station and issue time, then a validity period: two day/hour pairs joined by a slash, for example 2412/2518 — valid from the 24th at 1200 UTC to the 25th at 1800 UTC. The groups immediately after the validity line describe the prevailing forecast — the base conditions expected to dominate the period.

Change groups then describe deviations from that base. The four you must know:

BECMG — becoming

A permanent change expected to occur gradually within a stated window, after which the new conditions persist. BECMG 2418/2420 means the change takes place between 1800 and 2000 UTC on the 24th, and the new conditions hold from then on.

TEMPO — temporary

Temporary fluctuations expected to occur during a stated window, each lasting less than one hour and in total less than half the window. Conditions are expected to return to the prevailing forecast in between. TEMPO 2414/2418 4000 TSRA means brief thunderstorms with rain and 4 km visibility may occur on and off between 1400 and 1800 UTC.

FM — from

A rapid, more or less complete change at a specific time. FM241500 means that from 1500 UTC on the 24th the conditions that follow replace everything before them. An FM group effectively starts a new self-contained forecast paragraph.

PROB — probability

A stated probability — only ever PROB30 or PROB40 — that a set of conditions will occur. It often combines with TEMPO, as in PROB30 TEMPO 2416/2420 TSRA: a 30% chance of temporary thunderstorms in that window. A probability of 50% or higher is expressed as a BECMG or FM change instead, not a PROB.

Read a TAF as a base forecast plus a list of qualified exceptions. For any given hour, work out which groups apply to it and combine them.

Worked examples

Three decoded reports. Read the code, then the plain-English translation underneath.

Example 1 — a routine METAR

METAR OERK 241200Z 32012KT 9999 FEW040 38/09 Q1009 NOSIG

• METAR OERK — routine observation for Riyadh King Khalid International.
• 241200Z — taken on the 24th at 1200 UTC.
• 32012KT — wind from 320° at 12 knots.
• 9999 — visibility 10 km or more.
• FEW040 — a few clouds at 4,000 ft above the aerodrome; no significant weather.
• 38/09 — temperature 38 °C, dewpoint 9 °C — hot and dry.
• Q1009 — set the altimeter to 1009 hPa.
• NOSIG — no significant change expected in the next two hours.

In short: a hot, clear, settled afternoon with a light north-westerly breeze.

Example 2 — a METAR with significant weather

METAR OEJN 240630Z 21018G30KT 180V250 3000 +TSRA BKN018 FEW025CB 29/24 Q1006 RERA

• OEJN 240630Z — Jeddah, 24th at 0630 UTC.
• 21018G30KT 180V250 — wind from 210° at 18 knots gusting 30, varying between 180° and 250°.
• 3000 — visibility reduced to 3 km.
• +TSRA — a heavy thunderstorm with rain.
• BKN018 FEW025CB — broken cloud at 1,800 ft, with a few cumulonimbus at 2,500 ft.
• 29/24 — 29 °C over a 24 °C dewpoint — very humid.
• Q1006 — altimeter 1006 hPa.
• RERA — rain had also been observed recently before this report.

In short: an active thunderstorm over the field with gusty, shifting wind and poor visibility — not a moment to be on final.

Example 3 — a TAF

TAF OEDF 241100Z 2412/2518 30010KT 9999 SCT035 BECMG 2416/2418 14015KT TEMPO 2503/2508 4000 BR PROB30 2506/2509 0800 FG

• TAF OEDF 241100Z — forecast for Dammam King Fahd International, issued on the 24th at 1100 UTC.
• 2412/2518 — valid from the 24th at 1200 UTC to the 25th at 1800 UTC.
• 30010KT 9999 SCT035 — base forecast: wind from 300° at 10 knots, visibility 10 km or more, scattered cloud at 3,500 ft.
• BECMG 2416/2418 14015KT — between 1600 and 1800 UTC the wind becomes south-easterly at 15 knots and stays that way.
• TEMPO 2503/2508 4000 BR — between 0300 and 0800 UTC on the 25th, expect temporary drops to 4 km visibility in mist.
• PROB30 2506/2509 0800 FG — a 30% chance, between 0600 and 0900 UTC, of fog reducing visibility to 800 m.

In short: a fine afternoon, the wind backing to the south-east in the evening, then a humid night with mist and a real chance of early-morning fog.

Common pitfalls

• Times are Zulu, not local. Saudi local time is UTC+3. A METAR timed 241200Z describes 3 p.m. local. Mentally converting wrongly is the single most common decoding error.
• CAVOK is not "no information". CAVOK ("ceiling and visibility OK") replaces the visibility, weather and cloud groups when visibility is 10 km or more, there is no cloud below 5,000 ft (or below the highest minimum sector altitude, whichever is greater) and no cumulonimbus, and no significant weather. It is good news, not missing data.
• Cloud heights are above aerodrome level, not sea level. A BKN008 means 800 ft above the airport, which at a high-elevation field is a much higher pressure altitude than at sea level.
• "No cloud group" is ambiguous without context. An absent cloud group can mean genuinely clear, or that an automated station could not assess cloud — that is what NCD and /// indicate. Read the whole report.
• A METAR is already history. Even a fresh report is a snapshot from minutes ago. For what the weather will do, you need the TAF — and for anything beyond the TAF window, area forecasts and charts.
• Always use the latest issue. Check the issue time. An amended TAF (TAF AMD) supersedes the earlier one entirely; do not blend them.
• Remarks are not standardised. The RMK section follows national conventions and a code you recognise from one country may mean nothing, or something else, in another.
• Verify the conventions. Units, intervals and national remark formats should be checked against ICAO Annex 3 and the current AIP-KSA rather than assumed.