Definition
A weather forecast covering the conditions a pilot can expect along the route of flight between the departure and destination airports, typically including cloud cover, visibility, precipitation, icing, turbulence, and winds aloft for the time period of the flight.
Plain English
A weather report that tells you what the air is likely to be doing along the path you'll fly, between takeoff and landing.
Context Anchor
You encounter this term during a standard preflight weather briefing, when checking conditions along the route you plan to fly.
Derivation
From the French 'en route,' meaning 'on the way.' So an en route forecast is literally a forecast for the part of the flight that happens 'on the way' — between the airports, not at them.
Why Pilots Care
It supports fuel planning, route adjustments, and decisions about alternate airports when weather changes are expected along the flight path.
Grounding Statement
Picture the en route forecast as the weather you expect to fly through between takeoff and landing.
Intuition Check
Do not read “en route forecast” as only the forecast for your destination. It means the expected weather along the path you plan to fly.
Example Sentence 1
The en route forecast showed a band of moderate icing between 8,000 and 12,000 feet, so the pilot planned to cruise at 6,000 instead.
Example Sentence 2
Strong headwinds noted in the en route forecast prompted the pilot to add extra fuel.