Definition
A pre-flight summary of current and forecast weather conditions relevant to a planned flight, obtained from an authorized source such as Flight Service, an online aviation weather service, or a Direct User Access Terminal System (DUATS). It typically covers adverse conditions, synopsis, current conditions, en route forecast, destination forecast, winds aloft, NOTAMs, and any other information that affects the safety or legality of the flight.
Plain English
A package of weather information a pilot gets before flying, covering what the weather is doing now and what it's expected to do along the route, at the destination, and at any alternates.
Context Anchor
Pilots get a weather briefing before flight planning and may update it before takeoff or while en route if conditions are changing.
Derivation
Briefing comes from brief, meaning short or concise. In aviation, a briefing is not casual talk; it is a focused summary meant to help someone act correctly.
Why Pilots Care
It supplies the information needed to avoid weather hazards and make safe go/no-go and route decisions.
Intuition Check
Do not think of a weather briefing as simply checking a phone forecast. In aviation, it means a flight-focused weather summary for the route and timing of that specific flight.
Example Sentence 1
Before departing on the IFR flight to Denver, she called Flight Service for a standard weather briefing.
Example Sentence 2
After receiving the weather briefing, the pilot delayed departure due to forecast thunderstorms.