Decoding the METAR, the SKC-to-OVC Sky Cover Codes, and What Ceiling Really Means When You Call a Day Marginal VFR

A METAR is a routine aviation weather observation that tells you what the weather is doing right now at one specific airport - not what it will do later. The single most important fact hidden inside it is the ceiling, which is the height of the lowest broken (BKN) or overcast (OVC) layer, because that number, paired with visibility, decides your flight category and your VFR go/no-go call. In the example below, a 1,200-foot broken ceiling with 10 miles of visibility makes the day marginal VFR, since the category always defaults to the worse of the two values.

The weather briefing doesn’t keep you safe - reading it does. You can pull up every radar product and wall of text on your tablet, but if you can’t turn one line into a decision, you have a pretty screen and nothing more. This guide walks through a full METAR line by line so the string of letters and numbers reads like a sentence, not noise.

What Is a METAR (and How Is It Different from a Forecast)?

A METAR is an observation, not a prediction. It’s the ground truth - what’s happening at one airport at one moment in time. That’s the first thing to burn into your brain: an observation is a fact, while the Terminal Aerodrome Forecast (TAF) is a separate product built on prediction.

METARs are issued about once an hour, usually near the bottom of the hour. When conditions change quickly, the station kicks out a special observation marked SPECI - same format, just triggered by change instead of the clock.

Here’s the example line we’ll decode:

KMCI 221853Z 18012G19KT 10SM BKN012 OVC035 22/15 A2992

It sounds like noise. It isn’t. It’s a sentence.

How Do I Read the Station, Date, and Time in a METAR?

KMCI is the station identifier - your airport. This one is Kansas City. Every station in the lower 48 starts with K.

221853Z is the date and time. The first two digits (22) are the day of the month. The next four (1853) are the time, and here’s what trips up every new pilot: it’s in Zulu (Coordinated Universal Time). The whole aviation world runs on one clock so nobody does time-zone math while flying.

Learn your offset cold. On central daylight time, you are 5 hours behind Zulu, so an observation stamped 1853Z was taken at 1:53 p.m. local. Do that subtraction wrong and you might read three-hour-old weather and call it current.

What Do the Wind Numbers Mean?

Wind is always given as the direction it’s blowing from, referenced to true north in the written observation. 18012G19KT means the wind is from the south (180°) at 12 knots, gusting to 19.

That’s your first decision hiding in plain sight. If the runway runs east-west, a south wind at 12 gusting 19 is nearly a direct crosswind. Before you even look outside, the METAR told you to check the crosswind component against what you and your airplane can actually handle - your number, not just the airplane’s.

A few wind codes worth knowing:

• VRB means variable - the direction won’t pin down.
• Very light, variable winds at low speeds get spelled out by the automated station rather than assigned a steady direction, so don’t panic if the wind field looks unusual at near-calm speeds.

How Do I Read Visibility?

10SM means 10 statute miles, which is really shorthand for “10 or more” - as clear as it gets. Note that U.S. METAR visibility is in statute miles, not nautical, one of aviation’s little inconsistencies.

When visibility drops, you’ll see fractions: three-quarters of a mile written as 3/4, or one and a half miles as 1 1/2. Low visibility is where a lot of accident chains start, so give that number a hard look every single time.

What Do the Sky Cover Codes (SKC, FEW, SCT, BKN, OVC) Mean?

The observation divides the sky into layers and reports how much of each is covered, measured in eighths (oktas). Picture the sky over the field cut into eight equal pieces.

• SKC or CLR - Clear. SKC comes from a human observer; CLR comes from an automated station finding nothing below 12,000 feet. Same practical meaning to you.
• FEW - Few clouds, 1 to 2 eighths covered.
• SCT - Scattered, 3 to 4 eighths. Getting patchy, still plenty of blue.
• BKN - Broken, 5 to 7 eighths. More cloud than gap.
• OVC - Overcast, 8 eighths. The whole lid is closed.

Here is the single most important rule in this whole topic: a ceiling is the height of the lowest broken or overcast layer. Few and scattered do not count. Say it back to yourself - broken or overcast. The FAA cares about that definition, and so should you, because ceiling is one of the two numbers that decides your VFR fate.

In our line, BKN012 OVC035 means the broken layer is the lowest qualifying layer, so the ceiling is 1,200 feet - not 3,500. The overcast above it is real, but the ceiling is defined by the lowest broken-or-worse layer.

What Are the Four Flight Categories (VFR, MVFR, IFR, LIFR)?

These four categories are built from ceiling and visibility, and the category always goes to the worse of the two:

• VFR - Ceiling greater than 3,000 feet and visibility greater than 5 miles. A good day.
• Marginal VFR (MVFR) - Ceiling 1,000 to 3,000 feet, or visibility 3 to 5 miles. The apps paint this blue. It’s often legal, and it’s exactly the kind of day that quietly bites low-time pilots, because it looks flyable right up until the ceiling scrapes down another 200 feet while you’re out there.
• IFR - Ceiling 500 to below 1,000 feet, or visibility 1 to less than 3 miles.
• LIFR (Low IFR) - Ceiling under 500 feet, or visibility under 1 mile. The bottom of the world.

Our Kansas City example has a 1,200-foot ceiling and 10 miles of visibility. The visibility screams VFR, but the ceiling says marginal - and because the category defaults to the worse value, this is a marginal VFR day. A 1,200-foot broken layer means you’d be flying under a low lid, and if it lowers, your outs get smaller fast.

How Should I Handle a Marginal VFR Day as a New Pilot?

Picture it: you’re a fresh private pilot wanting to fly 40 miles to see family. The METAR reads 10 miles, broken 1,200, and the sun’s out under the deck. Every instinct says go. You can go. But ask yourself the instructor question every time: What does the trend look like, and what’s my out?

Follow these steps:

1. Check the neighbors. Read METARs from nearby stations and along your route, not just your departure field.
2. Read the trend, not just the snapshot. Look at the last few hours. A ceiling that started at 3,000 this morning and is now at 1,200 is coming down on you - the number on the page is the good news, not the bad.
3. Cross-check the forecast (TAF). The METAR is a snapshot; trend is a movie. You need both.
4. Define your out before you launch. Know where you’ll divert or turn around if the lid lowers.

What Do Temperature, Dew Point, and Altimeter Tell Me?

22/15 is the temperature and dew point: 22°C over 15°C, both always in Celsius. The trick worth its weight in gold is the spread between them. When the two numbers close in, the air is saturating, and saturated air near the surface means fog and low stratus.

A spread of 2 to 3 degrees and shrinking late in the day, heading into a cool evening, is the recipe for the field going IFR after sunset. In our line the spread is 7 degrees, so there’s no immediate fog worry - but watch it as the day cools. The temperature–dew point spread is your free fog crystal ball.

A2992 is the altimeter setting: 29.92 inches of mercury, the pressure you dial into your Kollsman window so your altitude reads true. It’s always prefixed with an A in the written observation.

Why Should I Always Read the Remarks (RMK)?

The remarks (RMK) section at the end is the part everybody skips and shouldn’t. This is where the station adds color: whether a human is augmenting the observation, peak wind gusts, when a rain shower began or ended, distant lightning, and sea-level pressure.

There’s real gold in remarks, and pilots skim past it because the main body already gave them a category. Don’t be that pilot - if a thunderstorm is walking toward the field, the remarks often whisper it first.

Reading the Whole METAR as One Story

The skill isn’t memorizing codes - anyone can do that. The pilot an examiner wants to sign off reads the whole line as one story:

Kansas City, early afternoon local. South wind 12 gusting 19 - a crosswind day, so check your component. Ten miles of visibility, you can see fine. But a broken deck at 1,200 feet makes it marginal VFR, so know your trend and your outs. Temperature–dew point spread is 7 degrees - no immediate fog, but watch it as the day cools. Altimeter 29.92, set it. Check the remarks for anything sneaking up.

One line of text, and you just built a flight decision out of it.

Here’s the homework, and actually do it: don’t wait until you need a METAR to read one. Tonight, pull up your home airport and one 200 miles away, and read them out loud. Say the ceiling. Say the category. Say the temperature–dew point spread and what it’s telling you. Do that daily for two weeks and you’ll never see noise again - you’ll see the story. And when the story says stay home, staying home is one of the most professional things a pilot ever does.

The observation format and category definitions here come straight from the FAA’s Aviation Weather Handbook and National Weather Service standards, and they’re worth reading with your own eyes.

Key Takeaways

• A METAR is a real-time observation, not a forecast; the TAF is the separate prediction product.
• A ceiling is the lowest broken (BKN) or overcast (OVC) layer - FEW and SCT never count as a ceiling.
• Flight category always defaults to the worse of ceiling or visibility: a 1,200-ft ceiling with 10 SM is marginal VFR.
• Watch the temperature–dew point spread; a small, shrinking spread near a cool evening signals fog and low stratus.
• Always read the remarks (RMK) and check the trend across time and nearby stations before committing.