METAR vs TAF: What's the Difference?

If you've looked at aviation weather data, you've seen two acronyms everywhere: METAR and TAF. They look similar, both are short, coded text strings issued for airport weather stations. But they serve very different purposes.

METAR tells you what the weather is right now. TAF tells you what the weather will be over the next 24–30 hours.

This guide explains both formats side by side, shows you how to read each one, and covers when you'd use one over the other.

Quick comparison

What is a METAR?

A METAR is a standardised weather observation issued by an airport weather station, typically every hour. It captures the exact conditions at the time of observation: wind, visibility, clouds, temperature, dewpoint, and pressure.

Here's an example from Chicago O'Hare (KORD):

METAR KORD 121853Z 27015G22KT 10SM SCT035 BKN080 04/M06 A2988 RMK AO2

This tells us:

• KORD: O'Hare International Airport
• 121853Z: 12th of the month, 18:53 UTC
• 27015G22KT: wind from 270° at 15 knots, gusting 22
• 10SM: 10 statute miles visibility
• SCT035 BKN080: scattered clouds at 3,500 ft, broken at 8,000 ft
• 04/M06: temperature 4 °C, dewpoint −6 °C
• A2988: altimeter 29.88 inHg

METARs are observations. They describe what the instruments measured at that moment. Nothing more, nothing less.

For a full breakdown of every METAR field, see our guide to reading METAR weather data.

What is a TAF?

A TAF (Terminal Aerodrome Forecast) is a weather forecast for the area immediately surrounding an airport, typically within 5 nautical miles of the station. TAFs are issued four times per day and cover the next 24 to 30 hours.

Unlike METARs, TAFs are written by human forecasters at meteorological offices, not generated automatically by station instruments.

Here's a TAF for the same station:

TAF KORD 121730Z 1218/1324 28012G20KT P6SM SCT040 BKN100
  FM130000 30008KT P6SM FEW050
  FM131200 33012KT P6SM SCT030
  TEMPO 1218/1222 BKN035

This looks denser, but it follows a predictable structure.

How to read a TAF

Let's break down that example:

Header line

TAF KORD 121730Z 1218/1324

The validity period 1218/1324 uses a day-hour format: first two digits are the day of the month, last two are the hour.

Base forecast

28012G20KT P6SM SCT040 BKN100

This is the prevailing forecast for the start of the period:

• 28012G20KT: wind from 280° at 12 knots, gusting 20
• P6SM: visibility greater than 6 statute miles (P = plus/more than)
• SCT040 BKN100: scattered at 4,000 ft, broken at 10,000 ft

Change groups

TAFs use change indicators to describe when and how conditions will shift:

In our example:

FM130000 30008KT P6SM FEW050

From the 13th at 00:00 UTC: wind shifts to 300° at 8 knots, visibility stays good, only a few clouds at 5,000 ft. This replaces all previous conditions.

TEMPO 1218/1222 BKN035

Temporarily between the 12th at 18:00 and the 12th at 22:00 UTC: expect broken clouds dropping to 3,500 ft. Between these fluctuations, the base forecast still applies.

Key differences in detail

1. Observation vs forecast

This is the fundamental split. A METAR is a measurement: data collected by instruments (thermometers, anemometers, ceilometers) at the station. A TAF is a prediction, a human forecaster's best estimate of what conditions will look like.

METARs can be wrong (instrument errors, siting issues), but they're never opinions. TAFs are always opinions, informed ones, but subject to the same limitations as any weather forecast.

2. Temporal scope

A METAR is a snapshot: conditions at one specific moment. A TAF covers a window of time and describes how conditions will evolve through change groups.

3. Temperature

METARs report temperature and dewpoint. TAFs do not include temperature at all (in the standard format; some extended TAFs add temperature forecasts, but this varies by country).

4. Who issues them

METARs come from automated stations (ASOS/AWOS in the US) or human observers. TAFs come from forecast offices, staffed by trained meteorologists who analyse model data, satellite imagery, and local patterns to produce the forecast.

5. Update frequency

When to use which

Use METAR when you need:

• Current conditions at a station right now
• Actual recorded temperatures (daily high tracking, climate records)
• Ground-truth data to verify forecasts
• Historical observations

Use TAF when you need:

• A look-ahead at expected conditions
• Flight planning (wind, visibility, ceiling forecasts)
• To know when weather is expected to change

For daily high temperature tracking, METARs are the only option. The TAF doesn't include temperature, and even if it did, a forecast isn't a record. The official daily high comes from the highest temperature observed across all METARs in a local day.

A real-world example

Say you want to know the daily high temperature at London City Airport (EGLC) on a given date.

The TAF might say:

TAF EGLC 121100Z 1212/1312 25010KT 9999 SCT030

This tells you: expect good visibility and scattered clouds. But it says nothing about temperature.

The METARs throughout the day will report actual temperatures hourly:

METAR EGLC 121250Z 24008KT 9999 SCT032 11/04 Q1021
METAR EGLC 121350Z 25012KT 9999 SCT030 12/03 Q1020
METAR EGLC 121450Z 25010KT 9999 SCT028 11/04 Q1020

The highest observation was 12 °C at 13:50 UTC. That's the daily high, sourced from METAR, not from any forecast.

Summary

Both formats are essential to aviation weather. But if you care about what actually happened (observed temperatures, recorded conditions, verifiable data), METARs are your source.

DailyHigh tracks METAR observations in real time across stations worldwide. See live data, daily high tracking, and temperature history on our stations page.