VFR, MVFR, IFR & LIFR — flight categories explained
Every colored badge on this site — and on most aviation weather products — is a flight category: a one-glance summary of ceiling and visibility. It's derived from the airport's latest METAR using one rule: the worse of ceiling and visibility sets the category.
Visual conditions. The pattern is comfortable and cross-countries work visually — though wind, gusts and density altitude can still make a VFR day a hard day.
Marginal VFR. Legal for VFR, but the margins that keep small problems small are thinner — terrain, towers and haze all matter more. Many personal-minimum sets treat MVFR as a no-go without a plan.
Instrument conditions. VFR flight is out; an instrument rating, a clearance and current approaches are the entry fee.
Low IFR. Even for instrument pilots this is approach-minimums territory — alternates, fuel and a healthy respect for the trend line are the story.
Two details that catch people
- Ceiling means BKN or OVC(or vertical visibility) — a few or scattered layer at 800 ft is not a ceiling, so a sky of SCT008 with 10 SM is still VFR by category. Whether you'd fly under it is a different question.
- The category is a summary, not a clearance.It says nothing about wind, gusts, crosswind, thunderstorms, icing or density altitude — a 25-gust-35 day can be firmly "VFR" and still park the fleet. That's why pilots layer personal minimums on top of the legal ones.
Using categories well
Categories shine as a trend instrument. A field sliding VFR → MVFR → IFR over three METARs tells you more than any single report; the "What changed?" card on every airport page shows exactly that diff, and the decoder computes the category for any report you paste. For the long view, the Flying Weather Index ranks US airports by their share of daylight VFR across two decades of observations.
Get pinged when the category changes
The Telegram bot watches your airport and messages you when it drops out of VFR — or crosses your own ceiling and visibility limits. Free for your home field.
⚠️ Educational reference — not for operational use. Category thresholds summarize FAA aviation weather product conventions; always get an official briefing before flight.