METAR and TAF decoder

How do you read a METAR or TAF?

Paste an aviation weather report and read every group in plain words, with the flight category, humidity and density altitude.

Weather report

Paste one METAR, SPECI or TAF, with or without its type word.

METAR EFHK

MVFR

Marginal visual flight rules, by the US convention: ceiling 2,500 ft (760 m), visibility 10 km or more.

Observation

Airport: Helsinki Vantaa Airport
Observed: day 13 at 10:50 UTC
Wind: From 220° at 12 kt
Wind direction: 190°–250°
Visibility: 10 km or more
Weather: Light showers of rain
Clouds: Few at 1,200 ft
Clouds: Broken at 2,500 ft, cumulonimbus
Temperature: 12 °C (54 °F)
Dew point: 9 °C (48 °F)
QNH: 1008 hPa (29.77 inHg)
Relative humidity: 82%
Elevation: 179 ft (55 m)
Pressure altitude: 320 ft (98 m)
Density altitude: 190 ft (58 m)

Airport names and elevations: OurAirports (public domain).

Trend: the next 2 hours

Trend: the next 2 hours
When	Change	Expected
Next 2 hours	Temporarily: spells of under an hour, less than half the time	4,000 m; Showers of rain

Group by group

Group by group
Group	Meaning
METAR	Routine aerodrome weather report (METAR)
EFHK	Station EFHK: Helsinki Vantaa Airport, Helsinki (Vantaa), Finland
131050Z	Observed on day 13 at 10:50 UTC
22012KT	From 220° at 12 kt (22 km/h)
190V250	Direction varying between 190° and 250°
9999	10 km or more
-SHRA	Light showers of rain
FEW012	Few (1–2 oktas) at 1,200 ft (370 m)
BKN025CB	Broken (5–7 oktas) at 2,500 ft (760 m), cumulonimbus
12/09	Temperature 12 °C (54 °F), dew point 9 °C (48 °F)
Q1008	QNH 1008 hPa (29.77 inHg)
TEMPO	Temporarily: spells of under an hour, less than half the time
4000	4,000 m
SHRA	Showers of rain

Paste an aviation weather report and read every group in plain words, with the flight category, humidity and density altitude.

How to use

Paste a METAR, SPECI or TAF into the box, or tap an example. The type word and a trailing = are optional.
Read the summary: the flight category, the weather in plain words, and the humidity. Every group is explained in the table below it, and a TAF's changes are listed as a timeline.
The airport's name, elevation and density altitude appear when the airport list has loaded.

How it works

A METAR is the routine weather observation of an airport, usually made every 30 or 60 minutes; a SPECI is a special one made when the weather changes significantly. A TAF is the airport's forecast for the next 9 to 30 hours. All three use the same short groups, defined by the World Meteorological Organization (WMO No. 306, FM 15, FM 16 and FM 51) and ICAO Annex 3, so a pilot anywhere can read them. The United States uses statute miles, inches of mercury and its own remarks (FAA AC 00-45H).

Each group has a fixed form: 24008KT is wind from 240° at 8 knots, 9999 is visibility of 10 km or more, BKN025CB is a broken layer of cumulonimbus at 2,500 ft, 07/05 is temperature and dew point in °C, and Q1021 is the sea-level pressure setting (QNH) in hectopascals. In a TAF, BECMG marks a gradual change, TEMPO short spells, FM a complete change from a time, and PROB30 or PROB40 a chance in percent.

Relative humidity comes from the temperature and dew point (Bolton 1980), density altitude from the QNH, temperature and the airport's elevation by the US National Weather Service method. The flight category follows the US convention (FAA AIM 7-1-7): LIFR below 500 ft ceiling or 1 statute mile, IFR below 1,000 ft or 3 miles, MVFR up to 3,000 ft or 5 miles, otherwise VFR.

Reports here are decoded as written: nothing is fetched, so check the time group (day of the month and UTC) to see how old a report is. Remarks (RMK) are national and are shown as they are. This is for learning and curiosity, never for flight planning.

Worked example

What does EGLL 130820Z 24008KT 0600 R27L/0550V0800U FG VV002 07/07 Q1021 say?

24008KT: wind from 240° at 8 knots. 0600: visibility 600 m.
R27L/0550V0800U: on runway 27L the runway visual range varies from 550 to 800 m and is rising.
FG VV002: fog, the sky is obscured and the vertical visibility is 200 ft.
07/07: temperature 7 °C and dew point 7 °C, so the relative humidity is 100%. Q1021: QNH 1021 hPa.

LIFR by the US convention: the visibility is only 0.37 statute miles.

Frequently asked questions

What is the difference between a METAR and a TAF?

A METAR tells what the weather is now at an airport; a TAF forecasts it for the next 9 to 30 hours. A METAR may end with a trend for the next two hours (NOSIG, BECMG or TEMPO).

What does CAVOK mean?

Ceiling and visibility OK: visibility 10 km or more, no cloud below 5,000 ft (or the highest minimum sector altitude), no cumulonimbus or towering cumulus, and no significant weather.

Why is the time in Z?

Z (Zulu) is UTC. 131050Z means the 13th day of the month at 10:50 UTC; the month and year are not given.

What are FEW, SCT, BKN and OVC?

Cloud cover in eighths of the sky (oktas): FEW 1–2, SCT scattered 3–4, BKN broken 5–7 and OVC overcast 8. The three digits after them are the base height in hundreds of feet above the airport.

What do the minus and plus signs mean?

Intensity: -RA is light rain, RA moderate rain and +RA heavy rain. VC means the weather is near the airport, within about 8 km, but not at it.

What is the ceiling?

The height of the lowest layer that covers more than half the sky (BKN or OVC), or the vertical visibility when the sky is obscured (VV). Pilots use it with the visibility to judge whether they can fly by sight.

Can it fetch the latest METAR for an airport?

Not yet. Paste a report from your weather briefing or an official service; nothing you paste is sent anywhere.

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