VFR, MVFR, IFR and LIFR explained
Four colours that summarise an airport's weather in one glance. Useful shorthand — as long as you know exactly what they measure, and what they leave out.
Last updated August 2026
Flight category is derived from just two numbers: the ceiling and the prevailing visibility. Whichever of the two is worse decides the category. Nothing else — not wind, not turbulence, not icing, not a thunderstorm sitting over the numbers — affects it.
The thresholds
| Category | Ceiling | Visibility | |
|---|---|---|---|
| VFR | Greater than 3,000 ft AGL | and | Greater than 5 SM |
| MVFR | 1,000 to 3,000 ft AGL | and/or | 3 to 5 SM |
| IFR | 500 to below 1,000 ft AGL | and/or | 1 to below 3 SM |
| LIFR | Below 500 ft AGL | and/or | Below 1 SM |
"And/or" matters: the worse of the two wins. A field with an 8,000-foot ceiling and 2 miles of visibility in mist is IFR, even though the sky above is nearly clear. Equally, a 700-foot overcast with 10 miles underneath is IFR on the ceiling alone.
MVFR — marginal VFR — is the category worth respecting most. It is legal for a VFR flight in most airspace, and it is also where a large share of weather-related accidents begin, because it degrades gradually and each individual step down feels survivable.
What counts as a ceiling
This is the rule that trips people up, so it is worth stating plainly: a ceiling is the lowest layer reported as broken (BKN), overcast (OVC), or an obscuration (VV). Few and scattered layers are not ceilings, no matter how low they are.
So SCT004 — scattered at 400 feet — contributes nothing to the
category. If visibility is good, that field reports VFR.
Change one letter to BKN004 and the same field is
LIFR.
A green dot does not mean the flight is a good idea. Scattered cloud at 400 feet with a VFR category is a real and common combination, and flying into it because the symbol was green is exactly the wrong use of this tool. The category is a filter for narrowing down which airports to look at properly — never a substitute for reading the actual observation.
Category is not the same as legal VFR
Flight category is a weather summary. Whether you may legally fly VFR is a regulatory question that depends on the airspace you are in, your altitude, and the time of day. In Class G below 1,200 feet AGL by day, one mile and clear of clouds can be legal — which is deep into the LIFR band. In Class B, the requirement is three miles and clear of clouds regardless of what colour the dot is.
Read the category as "how bad is it", and the regulations as "may I". They answer different questions and they disagree regularly.
Where the numbers come from
Ceiling and visibility both come from the METAR, so every caveat that applies to an observation applies here too. Automated stations measure the sky directly above the sensor, so a low deck a mile off the field may not appear at all. Visibility is the prevailing value — the greatest distance visible over at least half the horizon — so it can be considerably worse in one direction, which is often the direction you are approaching from.
And the category is only as fresh as the observation behind it. A field that stopped reporting three hours ago keeps showing its last colour indefinitely.
Using it in Flight Kneeboard
Airports are coloured by flight category by default, so a single glance across the map shows where the weather is. You can switch that colouring under Layers to wind, visibility, ceiling, sky coverage, temperature, dewpoint spread, altimeter or ATIS — swapping to ceiling or visibility directly is often more informative than the summary, precisely because it does not hide which of the two is the problem.
The TAF Breakdown on any airport shows forecast category as a timeline, and Weather → History charts up to eight days of past categories. Both are useful for the question the category alone cannot answer: not "is it bad now", but "is it getting better or worse, and when".