Reading a METAR

A METAR is a standardised weather observation report issued by airports worldwide. The name comes from the French METeorologique Aviation Reguliere (routine aviation weather report). METARs are issued every 30 minutes at most UK airports and provide a snapshot of current conditions. Learning to read them is a fundamental skill for any aviation enthusiast.

Example METAR

Let us decode a realistic METAR for Prestwick:

EGPK 051250Z 24015KT 9999 FEW040 12/06 Q1015

This looks cryptic at first, but each group of characters has a specific meaning. We will break it down left to right.

Group-by-Group Breakdown

1. Station Identifier: EGPK

The ICAO four-letter code for the airport. EGPK is Glasgow Prestwick. The "EG" prefix indicates a United Kingdom airport (England, Scotland, Wales, Northern Ireland all use EG).

Other nearby stations you might see:

• EGPF — Glasgow Airport
• EGPH — Edinburgh Airport
• EGPB — Sumburgh (Shetland)

2. Date and Time: 051250Z

The first two digits are the day of the month (05 = the 5th). The next four digits are the time in UTC (1250 = 12:50 UTC). The Z stands for Zulu, the military/aviation designation for UTC.

In summer (BST), add one hour to get local time. So 1250Z = 1350 BST. In winter, UTC equals UK local time.

3. Wind: 24015KT

Wind information is given as direction and speed:

• 240 — the direction the wind is blowing from, in degrees true (not magnetic). 240 degrees is from the south-west
• 15 — the wind speed in knots (KT)

Variations you might see:

• 24015G25KT — wind from 240 at 15 knots, gusting to 25 knots
• VRB05KT — variable direction at 5 knots (light wind with no consistent direction)
• 24015KT 200V280 — wind from 240 at 15 knots, varying between 200 and 280 degrees
• 00000KT — calm (no wind)

4. Visibility: 9999

Visibility in metres. 9999 means 10 kilometres or more — effectively unlimited visibility. In the UK, this is the maximum reported.

Other values you might see:

• 3000 — 3,000 metres visibility
• 0800 — 800 metres (fog territory)
• 0200 — 200 metres (dense fog)
• CAVOK — replaces both visibility and cloud groups. Means Ceiling And Visibility OK: visibility 10 km or more, no cloud below 5,000 feet, no significant weather

5. Weather Phenomena

Our example does not include a weather group, which means no significant weather at the time of observation. When weather is present, it appears between visibility and cloud, using standard abbreviations:

These are combined with intensity prefixes:

• - (minus) = light: -RA = light rain
• No prefix = moderate: RA = moderate rain
• + (plus) = heavy: +RA = heavy rain

Combinations are common: +TSRA = heavy thunderstorm with rain. -SHRA = light rain showers.

6. Cloud: FEW040

Cloud is reported in layers, with coverage (in oktas — eighths of the sky) and height in hundreds of feet above aerodrome level (AAL):

• FEW — few (1-2 oktas)
• 040 — at 4,000 feet AAL

Cloud coverage descriptors:

Multiple cloud layers may be reported:

FEW020 SCT040 BKN080

This means: few clouds at 2,000 feet, scattered at 4,000 feet, broken at 8,000 feet.

The ceiling is the lowest layer described as BKN or OVC. In the example above, the ceiling is 8,000 feet.

Special cloud types:

• CB — cumulonimbus (thunderstorm cloud): SCT040CB
• TCU — towering cumulus: FEW030TCU

7. Temperature and Dew Point: 12/06

Two numbers separated by a slash:

• 12 — temperature in degrees Celsius
• 06 — dew point in degrees Celsius

The dew point is the temperature at which the air becomes saturated and moisture condenses. The difference between temperature and dew point indicates humidity:

• Large gap (e.g., 12/06) — relatively dry air
• Small gap (e.g., 12/11) — very humid, fog or low cloud likely
• When temperature equals dew point (e.g., 08/08) — fog or mist is present or imminent

Sub-zero temperatures are shown with M (minus): M02/M05 means temperature -2, dew point -5.

8. Pressure: Q1015

The QNH — the atmospheric pressure adjusted to mean sea level, in hectopascals (hPa).

• Q — indicates QNH follows
• 1015 — 1015 hectopascals

Pilots set this value on their altimeters to read altitude above mean sea level. Standard pressure is 1013.25 hPa.

• High QNH (above 1013) — generally fair weather, high pressure
• Low QNH (below 1013) — generally unsettled weather, low pressure
• Very low QNH (below 990) — deep low pressure, likely stormy conditions

More Complex Prestwick METARs

Here are some realistic examples for different conditions:

Windy Day

EGPK 051420Z 26025G38KT 9999 SCT030 BKN050 09/04 Q0998

Wind from 260 degrees at 25 knots gusting 38 knots. Visibility 10 km plus. Scattered cloud at 3,000 feet, broken at 5,000 feet. Temperature 9, dew point 4. QNH 998 (low pressure — windy conditions expected).

Haar Event

EGPK 050830Z 19008KT 0600 FG VV001 08/08 Q1022

Wind from 190 at 8 knots. Visibility 600 metres in fog. Vertical visibility (VV) 100 feet — the fog layer extends from the surface and you cannot see a cloud base through it. Temperature and dew point both 8 — the air is fully saturated. QNH 1022.

The VV001 notation replaces cloud groups when the sky is obscured. VV followed by a three-digit number gives the vertical visibility in hundreds of feet.

After a Cold Front

EGPK 051530Z 30018G28KT 9999 -SHRA FEW025CB SCT035 07/02 Q1008

Wind from 300 at 18 gusting 28 knots. Visibility 10 km plus despite light rain showers (-SHRA). Few cumulonimbus at 2,500 feet, scattered cloud at 3,500 feet. Temperature 7, dew point 2. QNH 1008.

This is typical post-frontal weather at Prestwick — blustery north-westerly wind with showers and dramatic skies. Excellent photography conditions between the showers.

Where to Get METARs

• aviationweather.gov — the NOAA Aviation Weather Center provides METARs for airports worldwide
• Met Office — UK-specific aviation weather
• ATIS — listening to ATIS on 121.125 MHz gives you the same information in spoken form
• Apps — aviation weather apps like Windy, AeroWeather, or ForeFlight display decoded METARs
• egpk.info — may display current weather conditions for Prestwick