The Ultimate Guide to Reading METAR & TAF Codes | 2026 Pilot Guide
- PPL Club
- 5 days ago
- 5 min read
Updated: 4 days ago
You are planning your first cross-country flight. You open your flight planning app, ready to go, and you are greeted with this:
EGBB 091020Z 23015G25KT 9999 +RA SCT025TCU 18/13 Q1002
If that looks like a cat walked across a keyboard, you are not alone.
Learning to decode METARs (Actual Weather) and TAFs (Forecast Weather) is a fundamental skill for any pilot. It isn't just about passing the Meteorology PPL exam; it is about making safe "Go/No-Go" decisions.
In this comprehensive guide, we will strip away the jargon and give you a complete "Rosetta Stone" for UK aviation weather.
Key Takeaways (Summary)
METAR = Current weather reports (Actual). Updated every 30 mins.
TAF = Future weather predictions (Forecast). Valid for 9 to 30 hours.
Rule: If the wind direction is written, it is True North. If it is spoken, it is Magnetic North.
CAVOK = "Cloud and Visibility OK" (Safe flying conditions).
9999 = Visibility is 10km or more.
Understanding these strings is more than just an academic exercise; it is your first line of defence against inadvertent flight into Instrument Meteorological Conditions (IMC).
While the summary above gives you the basics, the devil is in the detail. We have structured this guide to follow the standard ICAO format used across the UK and Europe, ensuring you can interpret complex weather patterns instantly—before you even walk out to the aircraft.
What is a METAR?
METAR stands for METeorological Aerodrome Report. It is a snapshot of the weather at a specific airport right now. In the UK, these are typically updated every 30 minutes (usually at 20 minutes past and 50 minutes past the hour).
METAR vs. ATIS: What is the difference?
While a METAR is a coded text report, ATIS (Automatic Terminal Information Service) is a voice broadcast you listen to on the radio. The ATIS contains the METAR information but adds operational details like the runway in use and altimeter settings.
The "Anatomy" of a METAR String
Let's decode our original example line-by-line to see how it works.
Location (EGBB): The ICAO code for the airport (Birmingham).
Date/Time (091020Z): The 9th day of the month at 10:20 Zulu (UTC).
Wind (23015G25KT): Coming from 230 degrees (True) at 15 knots, Gusting to 25 knots.
Struggling to calculate crosswind components? Use our Free Crosswind Calculator.
Visibility (9999): 10km or more (effectively "Unlimited").
Weather (+RA): Heavy Rain. The + indicates heavy intensity.
Cloud (SCT025TCU): Scattered clouds at 2,500ft, specifically Towering Cumulus.
Temperature (18/13): Air Temp 18°C, Dewpoint 13°C.
Pressure (Q1002): QNH is 1002 hectopascals (millibars).
The Essential Weather Codes Cheat Sheet
The wind and numbers are easy maths. The hard part is the "Weather Phenomenon" codes. Here are the ones you must know for the UK PPL exams:
While less common, seeing these codes should trigger immediate caution:
SQ: Squall (Sudden, sharp increase in wind speed).
WS: Wind Shear (Dangerous changes in wind speed/direction on approach).
VA: Volcanic Ash.
Advanced: Runway Visual Range (RVR)
In poor visibility, you might see an extra group of numbers after the visibility, like R24/P1500. This stands for Runway Visual Range. It is used when visibility drops below 1,500m. Instruments along the runway measure exactly how far a pilot can see down that specific runway.
R24/P1500: On Runway 24, visibility is Plus (more than) 1,500m.
R09/0400: On Runway 09, visibility is only 400m.
CAVOK vs. NSC: What’s the difference?
You will often see these two abbreviations. They both sound like "good news," but they mean different things.
CAVOK (Cloud and Visibility OK)
This is the pilot's dream. It explicitly means:
Visibility is 10km or more.
No clouds below 5,000ft (or the MSA).
No significant weather (no rain, snow, or CBs).
NSC (No Significant Cloud)
This simply means there are no clouds below 5,000ft and no Towering Cumulus/Cb.
The Trap: You can have NSC but still have terrible visibility (fog)! Always check the visibility numbers carefully.
What is a TAF? (Forecasting the Future)
TAF stands for Terminal Aerodrome Forecast. While a METAR tells you what is happening now, a TAF tells you what is likely to happen later.
Understanding "Change Groups"
The most confusing part of a TAF is how the weather shifts over time.
BECMG (Becoming): A permanent change is coming.
Example: BECMG 1214 2000 means between 12:00 and 14:00, the visibility will drop to 2000m and stay there.
TEMPO (Temporary): A short-lived change (less than an hour at a time).
Example: TEMPO 1214 4000 RA means it will mostly be fine, but you might get brief rain showers between 12:00 and 14:00.
PROB30 / PROB40: The percentage probability of something happening.
Safety Rule: If you see PROB30 TSRA (30% chance of Thunderstorms), treat it as a 100% chance and plan accordingly.
Case Study: A Winter Day at Leeds Bradford (EGNM)
Real-world application is key. Let’s look at a difficult winter report for Leeds Bradford, one of the UK's highest airports.
EGNM 120850Z 33025G38KT 3000 +SHSN BKN012CB 01/M02 Q0998
The Analysis:
Wind: Severe. 25 knots gusting 38 knots. This is likely beyond the crosswind limit for most student pilots (check your [Aircraft POH]).
Visibility: 3000m. Not IFR, but poor for VFR navigation.
Weather: Heavy Snow Showers (+SHSN).
Temp/Dew: The spread is 3°C (1°C and -2°C). Carb icing is a significant risk here.
Decision: This is a definitive No-Go for a PPL student.
Common Student Mistakes to Avoid
In the PPL Meteorology Exam, the CAA loves to test these specific pitfalls:
True vs. Magnetic:
METAR/TAF wind directions are always True North.
Wind from the Tower (ATIS/Radio) is Magnetic North.
Mnemonic: "If it's written, it's True. If it's said, it's Magnetic."
Cloud Heights: Cloud heights are always Height Above Aerodrome Level (AAL), not sea level.
9999 isn't Infinity: It just means "10km or more." It could be 10km, or it could be 50km.
Where to find Official UK METARs
Don't rely on generic weather apps. For flying, use official sources:
The Met Office Aviation Web: The primary source for UK pilots (Free account required).
Ready to Practice?
The key to passing your exam—and staying safe—is practice. Don't just memorise the codes; check the METARs for your local airport every morning and see if they match the weather outside your window.
Ready to test your knowledge?
Try out PPL Mock Exams
Frequently Asked Questions (FAQ)
What is the difference between METAR and ATIS?
A METAR is a coded text report updated every 30 minutes. ATIS (Automatic Terminal Information Service) is a voice broadcast (often recorded) that pilots listen to on the radio, which includes the METAR plus operational info like the runway in use.
How do i read cloud coverage codes?
Cloud coverage is measured in "Oktas" (eighths of the sky):
FEW: 1-2 Oktas
SCT (Scattered): 3-4 Oktas
BKN (Broken): 5-7 Oktas (This constitutes a "Cloud Ceiling")
OVC (Overcast): 8 Oktas
Why are temperatures and dewpoints important?
If the Temperature and Dewpoint are close together (within 2°C), the air is saturated. This means Fog or Low Cloud is highly likely to form.
