METAR and TAF Abbreviations: The Complete Decoder Table
The weather codes in a METAR are not arbitrary letters. They are built from four small vocabularies that combine in a fixed order: an intensity marker, then a descriptor, then one to three phenomena. Learn the four lists and you can read a combination you have never seen before.
+TSRA is not an entry in a dictionary. It is heavy, thunderstorm, rain — assembled on the spot, the same way the forecaster assembled it.
How a weather group is built#
Read left to right: intensity, then descriptor, then phenomenon. Any of the three can be absent. VC replaces the intensity marker to mean in the vicinity — between about 8 and 16 kilometres from the aerodrome, not at it.
| Position | Codes | Meaning |
|---|---|---|
| Intensity | -, none, + | Light, moderate, heavy |
| Proximity | VC | In the vicinity of the aerodrome, not over it |
| Descriptor | MI BC PR DR BL SH TS FZ | Shallow, patches, partial, drifting, blowing, showers, thunderstorm, freezing |
| Phenomenon | RA SN DZ GR … | The precipitation or obscuration itself |
So -SHRA is light showers of rain, +TSRA is a heavy thunderstorm with rain, and FZDZ is freezing drizzle — which is the one that ruins aircraft.
Descriptors#
| Code | Meaning | Why it matters |
|---|---|---|
| MI | Shallow | Fog under about two metres deep — the runway may be clear at eye level |
| BC | Patches | Not continuous; conditions can change between one end of the runway and the other |
| PR | Partial | Covering part of the aerodrome only |
| DR | Low drifting | Below eye level — blowing snow or dust under two metres |
| BL | Blowing | Raised above eye level; reduces visibility properly |
| SH | Showers | Convective, so intermittent and often sharp |
| TS | Thunderstorm | Lightning present; implies severe turbulence and possible hail |
| FZ | Freezing | Supercooled — freezes on contact with the airframe or the runway |
Precipitation and obscuration#
| Code | Meaning | Code | Meaning |
|---|---|---|---|
| DZ | Drizzle | BR | Mist — visibility 1,000 m or more |
| RA | Rain | FG | Fog — visibility under 1,000 m |
| SN | Snow | FU | Smoke |
| SG | Snow grains | HZ | Haze |
| PL | Ice pellets | DU | Widespread dust |
| GR | Hail, 5 mm or larger | SA | Sand |
| GS | Small hail or snow pellets | VA | Volcanic ash |
| IC | Ice crystals | PO | Dust or sand whirls |
| UP | Unidentified precipitation | SQ | Squall |
| NSW | No significant weather | FC | Funnel cloud |
BR and FG are the same phenomenon divided by a number: 1,000 metres. That single threshold decides which of the two appears.
Cloud, and the groups that replace it#
| Code | Meaning |
|---|---|
| FEW | 1–2 oktas of the sky |
| SCT | 3–4 oktas — scattered |
| BKN | 5–7 oktas — broken, counts as a ceiling |
| OVC | 8 oktas — overcast, counts as a ceiling |
| NSC | No significant cloud below 5,000 ft or the highest minimum sector altitude |
| NCD | No cloud detected — an automated station reporting nothing |
| SKC / CLR | Sky clear |
| VV/// | Sky obscured, vertical visibility not measurable |
| CB | Cumulonimbus, appended to a layer |
| TCU | Towering cumulus, appended to a layer |
| CAVOK | Ceiling and visibility OK — replaces visibility, weather and cloud groups together |
CAVOK is not a compliment; it is a defined state. Visibility 10 km or more, no cloud below 5,000 ft or the minimum sector altitude, no CB or TCU, and no significant weather.
Trend, runway and report-status groups#
| Code | Where | Meaning |
|---|---|---|
| NOSIG | METAR trend | No significant change expected in the next two hours |
| BECMG | Both | Permanent change, occurring gradually |
| TEMPO | Both | Temporary fluctuations, each under an hour |
| PROB30 / PROB40 | TAF | 30 or 40 per cent probability |
| FM | TAF | From this time — a rapid, complete change |
| AUTO | METAR | Fully automated observation, no human observer |
| COR | METAR | Corrected report, replaces the earlier one |
| AMD | TAF | Amended forecast, replaces the earlier one |
| R27/0900 | METAR | Runway visual range: 900 m on runway 27 |
| R27/CLRD70 | METAR | Runway 27 cleared, friction coefficient 0.70 |
| WS RWY24 | METAR | Windshear reported on the approach or departure path of runway 24 |
| RMK | METAR | Remarks — national additions, formats vary by state |
Everything after RMK is outside the international standard. North American remarks are rich and worth learning; elsewhere the section is often empty.
Combinations you should recognise on sight#
- FZRA — freezing rain. Supercooled droplets that freeze on the airframe on contact, and among the most dangerous conditions in aviation.
- +TSGR — heavy thunderstorm with hail. Structural damage territory; not a weather to be near.
- VCTS — thunderstorms in the vicinity. Nothing over the field yet, and a reason to expect windshear.
- BLSN — blowing snow, visibility down at eye level even when the sky is clear.
- MIFG — shallow fog. The runway can be invisible from the flight deck while the tower reports good visibility.
- SHRA BKN008 — showers with a broken layer at 800 ft; the classic marginal-approach combination.
Our decoder handles all of these and prints the expansion in your language. It parses standard formats and can be wrong about a truncated or non-standard report — always read the raw text alongside it.
Frequently asked questions
What does CAVOK mean?
Ceiling and Visibility OK — a defined state, not a general description. It requires visibility of 10 kilometres or more, no cloud below 5,000 feet or below the highest minimum sector altitude, whichever is greater, no cumulonimbus or towering cumulus at any height, and no significant weather. When those conditions are met, CAVOK replaces the visibility, weather and cloud groups in one word.
What does FZRA mean in a METAR?
Freezing rain: rain falling as liquid through air below freezing, which freezes on contact with the airframe or the runway. It is one of the most hazardous conditions reported, because it produces clear ice quickly over large areas of the wing, and it also produces some of the worst braking action on the ground. FZDZ, freezing drizzle, is the same mechanism with smaller droplets and is nearly as serious.
How are METAR weather codes constructed?
From four small vocabularies read left to right: an intensity marker (- for light, nothing for moderate, + for heavy, or VC for in the vicinity), a descriptor (MI, BC, PR, DR, BL, SH, TS, FZ), then one to three phenomena (RA, SN, GR, FG and so on). Any part can be absent. That is why you can read a combination you have never seen: +TSRA is simply heavy, thunderstorm, rain, and BLSN is blowing snow.
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