How to Read a METAR

What is a METAR?

A METAR (Meteorological Aerodrome Report) is a standardized weather observation issued at airports, typically every hour on the hour. They are the primary source of current conditions for aviation preflight planning and are sourced from aviationweather.gov.

A Real METAR — Fully Decoded

Let’s decode a complete METAR from San Francisco International:

Field	Value	Meaning
Station ID	KSFO	San Francisco International Airport (ICAO)
Date/Time	201856Z	20th of the month, 18:56 UTC (Zulu)
Wind	28012KT	From 280° (west) at 12 knots
Visibility	10SM	10 statute miles
Clouds	FEW025 SCT040 BKN080	Few at 2,500, scattered at 4,000, broken at 8,000 ft AGL
Temperature/Dew Point	17/09	17°C temp, 9°C dew point (spread = 8°)
Altimeter	A2992	29.92 inHg — set your Kollsman window here
Remarks	AO2 SLP132 T01720094	Automated station, sea level pressure 1013.2 hPa, precise temp 17.2°C

Every METAR Field Explained

Wind

Format: DDDSSKT or DDDSSGSSGKT for gusts. Direction in magnetic degrees, speed in knots. VRB means variable direction (wind below 6 knots). Example: 24018G28KT = from 240° at 18 knots gusting to 28 knots.

Variable winds with speed ≥6 knots also include: 210V280 (variable between 210 and 280 degrees).

Visibility

Reported in statute miles (SM) in the US. Fractions indicate low visibility: 1/2SM, 1 1/4SM. Values below 3 SM trigger IFR conditions. Below 1 SM is Low IFR (LIFR).

Cloud Layers

Code	Coverage	Oktas
SKC / CLR	Sky clear	0
FEW	Few	1–2 oktas
SCT	Scattered	3–4 oktas
BKN	Broken	5–7 oktas (ceiling)
OVC	Overcast	8 oktas (ceiling)
VV	Vertical visibility	Into obscuration

Heights are in hundreds of feet AGL. BKN015 = broken ceiling at 1,500 ft AGL.

Temperature and Dew Point

In Celsius. A dew point spread under 4°C suggests potential fog formation. Negative values are prefixed with M: M02/M08 = -2°C / -8°C.

Altimeter Setting

In the US, prefixed with A and given in hundredths of inches of mercury: A3002 = 30.02 inHg. Always set your altimeter before engine start and again before descent.

Flight Categories

Category	Ceiling	Visibility
VFR	Above 3,000 ft AGL	Greater than 5 SM
MVFR	1,000–3,000 ft AGL	3–5 SM
IFR	500–999 ft AGL	1–3 SM
LIFR	Below 500 ft AGL	Less than 1 SM

Remarks (RMK) Section

Common remarks:

• AO1 / AO2 — Automated station without / with precipitation discriminator
• SLP — Sea level pressure (e.g. SLP132 = 1013.2 hPa)
• T — Precise temperature/dew point (e.g. T01720094 = 17.2°C / 9.4°C)
• PK WND — Peak wind in the last hour (e.g. PK WND 28035/1742)
• TSNO — Thunderstorm information not available
• $ — Maintenance needed on the automated station

SPECI — Special Observation Reports

A SPECI is issued between routine METAR observations when conditions change significantly — ceiling drops below 3,000 ft, visibility drops below 3 SM, or a thunderstorm begins or ends. Always check for SPECIs when conditions are changing.