Definition
The lowest weather conditions — typically expressed as visibility and cloud ceiling — under which a pilot is legally permitted to operate an aircraft under a given set of rules (such as VFR or IFR) or for a particular flight operation, airport, or pilot certificate level.
Plain English
The worst weather you are still legally allowed to fly in. If the weather is below these limits, you are not allowed to fly that flight under those rules.
Context Anchor
Used during flight planning, go/no-go decisions, training lessons, and risk management before and during a flight.
Derivation
Minimum comes from the Latin minimus, meaning smallest or least. So weather minimums are the least acceptable weather conditions — the floor below which flight is not permitted.
Why Pilots Care
They determine whether a planned flight can depart or continue without violating regulations or compromising safety.
Intuition Check
Minimums are not a goal and not a promise that the flight will be easy. They are the lowest acceptable limits; good judgment often means staying well above them.
Example Sentence 1
The ceiling dropped to 800 feet, which was below VFR weather minimums, so the student and instructor cancelled the lesson.
Example Sentence 2
Approach minimums for the ILS were 200 feet ceiling and one-half mile visibility.