Decoding the METAR, Reading the Coded Observation Left to Right, and the Temperature-Dewpoint Spread That Tells You When the Airport Is About to Disappear

A METAR (Meteorological Aerodrome Report) is a coded observation of the weather actually happening at an airport right now - not a forecast, but measured truth. It always follows the same left-to-right order: station, time, wind, visibility, weather, sky condition, temperature/dewpoint, and altimeter. Once you know that fixed sequence, the string of letters and numbers reads like a plain-language sentence, and the temperature-dewpoint spread near the end tells you when an airport is about to disappear into fog.

What Is a METAR and Why Does It Matter?

A METAR is the coded observation sitting at the front of every weather briefing. It reports what is measured and happening at that airport at a specific moment - no guessing, no prediction.

That distinction matters. A forecast tells you what someone thinks the weather will do. The METAR tells you what it is doing. If you can’t read the truth on the ground, you have no business betting on the forecast. Learn the METAR first, and everything downstream gets easier.

How Do You Read a METAR From Left to Right?

Every METAR in the United States follows the same skeleton, in the same order, every time:

1. Station identifier
2. Time (in Zulu)
3. Wind
4. Visibility
5. Present weather codes
6. Sky condition
7. Temperature/dewpoint
8. Altimeter setting
9. Remarks (when present)

The gift of the METAR is that this order never changes. Once you memorize the sequence, you always know what you’re looking at - even before you decode a single group.

What Do the Station Identifier and Time Mean?

The report opens with a four-letter station identifier. In the lower 48 states, the first letter is almost always K, a regional code, followed by the three letters of the field. KLAX is Los Angeles, KORD is Chicago O’Hare, KJFK is Kennedy. See the four letters and you know whose weather you’re reading.

Next comes the time: six digits followed by a Z. That Z means Zulu - Coordinated Universal Time, not your local clock. A report stamped 1753Z was taken at 1753 Zulu, and you must convert back to your time zone to know how old it is.

Why Zulu? Because weather doesn’t care what time zone you’re standing in, and a pilot flying from Denver to Kansas City crosses one. One clock works for everybody. Learn your local offset cold: in summer, Eastern is 4 hours behind Zulu and Pacific is 7 hours behind.

The time also tells you the report’s age. A METAR is usually issued about once an hour, near 53 minutes past. But when weather changes fast, the station issues a special report, marked with the letters SPECI. When you see SPECI, sit up - the airport didn’t want to wait for the top of the hour.

How Do You Read the Wind in a METAR?

The wind group is where the METAR starts talking to the pilot. You’ll see three digits, then two digits, then KT.

The first three digits are the direction the wind is coming from, in degrees. Here’s the catch that trips everyone: on the printed METAR, that direction is referenced to true north. But when a tower or automated voice reads the wind to you over the radio, it’s given in magnetic. Same wind, two references. The number on the page and the number in your headset may differ by a few degrees - that’s not an error, that’s the reference.

The next two digits are the speed in knots. If you see the letter G, that’s a gust. So 24015G25KT means wind from 240 true, 15 knots, gusting 25.

Don’t stop at the steady wind - read the gust. The spread between steady wind and gust is the number that decides whether your crosswind landing is a non-event or a rodeo. The gust is the one that reaches out and grabs your wing on short final.

Two special cases:

• Calm wind prints as all zeros.
• Variable wind prints as VRB when it can’t settle on a direction. Variable light wind on a hot afternoon means the airport can’t tell you which runway to favor - watch the windsock yourself.

What Do the Visibility and Weather Codes Mean?

Visibility in a U.S. METAR prints in statute miles with the letters SM. 10SM means ten statute miles - you can see forever. When that number drops, pay attention. Fractions are written out, like 1 1/2 or 3/4.

The moment visibility drops below 3 miles and the ceiling drops with it, you’ve left plain VFR and entered marginal territory. That’s a decision point, not a footnote.

The present weather codes look the most like a foreign language and are actually the most logical piece once you have the key. They’re built from an intensity sign plus two-letter groups:

• Minus (−) = light
• Plus (+) = heavy
• No sign = moderate

The common two-letter codes:

• RA = rain
• SN = snow
• BR = mist (a French holdover; visibility coming down but not yet fog)
• FG = fog
• HZ = haze
• DZ = drizzle
• TS = thunderstorm (the one that should stop you cold)

There are modifiers too: SH for showers and FZ for freezing. FZRA (freezing rain) is about the most dangerous line a light-airplane METAR can print, because that’s ice bonding to your airframe the instant it touches.

So a code reading −RA BR decodes to light rain and mist. Say it out loud - it’s not a cipher, it’s shorthand, and now it’s your shorthand.

How Do You Read the Sky Condition and Ceiling?

The sky is reported in layers, each a three-letter code plus a height. The code tells you how much of the sky is covered:

• FEW = few
• SCT = scattered
• BKN = broken
• OVC = overcast

The three numbers after the code give the layer’s height in hundreds of feet above the airport. So BKN007 is a broken layer at 700 feet. The trick is simple: add two zeros. 007 becomes 700 feet. 250 becomes 25,000 feet.

Broken or overcast is what we call a ceiling - the lowest layer covering more than half the sky. It’s effectively a lid on your day.

If it’s clear, automated stations print SKC or CLR, meaning nothing below 12,000 feet. Blue sky. Go flying.

What Is the Temperature-Dewpoint Spread and Why Does It Matter?

After the sky, you get two numbers separated by a slash: temperature / dewpoint, both in Celsius. An M in front means minus (below zero).

Everybody reads the temperature and skips the dewpoint. Don’t. The dewpoint is the temperature at which the air can no longer hold its moisture and it turns to visible water - fog and clouds.

The distance between the two numbers is called the spread, and it’s one of the most quietly useful figures on the whole report.

• Wide spread (e.g., 15°C / 2°C, a 13-degree spread) means dry air - fog is not your problem today.
• Narrow spread (e.g., 12°C / 11°C, a 1-degree spread) means the air is saturated or nearly so, and the airport is one temperature drop away from disappearing into fog.

Here’s how that plays out. You’re planning an evening flight home. The METAR shows clear skies, 10 miles visibility - perfect. But the temperature is 14°C and the dewpoint is 13°C: a 1-degree spread. After sunset, the ground cools, the temperature falls, and the moment it touches the dewpoint, invisible moisture condenses into radiation fog and fills the valley like milk poured into a bowl. The METAR said clear. The spread said don’t count on it lasting.

On your checkride, the examiner is looking for exactly this. Not just whether you can decode the symbols, but whether you can read a temperature-dewpoint spread and say what the airport will do in three hours. That’s the pilot they want to sign off - the one who sees the fog before it’s there.

What Does the Altimeter Setting Tell You?

The altimeter setting prints as the letter A and four digits. A3001 is a setting of 30.01 inches of mercury - the number you twist into your Kollsman window so your altitude reads honestly.

Miss it by a tenth and you’re off by about 100 feet. In the mountains, at night, near terrain, 100 feet is a real number. Set it every time.

What Goes in the Remarks Section?

After the altimeter, you may find a remarks section kicked off by the letters RMK. This is where the station tucks in extra detail: when a special report fired, a more precise sea-level pressure, or a note that a thunderstorm is building to the northwest.

Don’t ignore remarks. It’s where the observer or automated station tells you what didn’t fit the format - the margin notes, which are often the whole story.

How Do You Put the Whole METAR Together?

Reading a METAR one letter at a time isn’t the goal. Reading it as a sentence is. Run the sequence and let each group answer a question:

• Station - where am I reading?
• Time in Zulu - how fresh is this?
• Wind with the gust - which runway, and how much workload?
• Visibility - can I see?
• Weather codes - what’s falling out of the sky?
• Sky condition - where’s the ceiling?
• Temperature / dewpoint - what’s the spread, and what’s coming?
• Altimeter - what altitude should I fly?
• Remarks - what did the format leave out?

Read left to right, same order every time, and the ransom note turns into a paragraph. That paragraph tells you the single most honest thing in your whole briefing: not what someone thinks the weather will do, but what it is doing right now on that field.

A Practice Drill for Your Next Flight

Before you open any forecast, pull the METAR for your departure, your destination, and one field along the way. Read all three out loud. Then find the temperature-dewpoint spread on each and say whether it’s opening up or closing down.

Do that ten flights in a row and you’ll stop seeing letters and start seeing weather - and you’ll catch the fog while it’s still just two numbers getting close. Best of all, this is free practice you can do from your couch tonight. The observations are public.

The format and codes here come straight out of the FAA’s Aviation Weather Handbook and National Weather Service coding standards, and it’s worth reading the source yourself.

Key Takeaways

• A METAR is an observation, not a forecast - it reports the measured truth at an airport right now, always in the same left-to-right order.
• Time is in Zulu (UTC); learn your local offset (summer: Eastern −4, Pacific −7) so you know how old the report is.
• Read the gust, not just the steady wind - the gust is what challenges you on short final; printed wind is true north, radio-reported wind is magnetic.
• Sky heights are in hundreds of feet (add two zeros), and broken or overcast layers form the ceiling.
• The temperature-dewpoint spread is your fog predictor: a narrow spread (1–2°C) means the airport can vanish into fog after a small temperature drop.