Definition
A forecast product that predicts wind direction, wind speed, and air temperature at specified altitudes above selected reporting locations, valid for set times during the forecast period. Winds are given in true direction (not magnetic) and in knots; temperatures are given in degrees Celsius. The forecast is issued for standard altitudes such as 3,000, 6,000, 9,000, 12,000, 18,000, 24,000, 30,000, 34,000, and 39,000 feet, with temperatures omitted for the level closest to the station and for altitudes within 2,500 feet of station elevation.
Plain English
A forecast that tells pilots what the wind and air temperature are expected to be at different altitudes above various points across the country, at specific times.
Context Anchor
Seen during preflight weather planning, especially when choosing an altitude and estimating groundspeed, fuel use, and time en route.
Derivation
"Aloft" comes from Old Norse "á lopt," meaning "in the air" or "up high." In aviation it specifically refers to conditions above the surface, distinguishing this forecast from surface weather reports.
Why Pilots Care
Allows selection of the most fuel-efficient altitude while avoiding strong headwinds, icing levels, or turbulence.
Grounding Statement
A calm day on the ground can still have strong wind a few thousand feet above it.
Intuition Check
Do not assume this forecast describes the wind you feel at the airport surface. It describes expected wind and temperature at altitude, and it is still a forecast, not a live measurement.
Example Sentence 1
Before departure, the pilot checked the winds and temperatures aloft forecast and chose 9,000 feet for a stronger tailwind on the eastbound leg.
Example Sentence 2
At 12,000 feet the forecast showed winds from 240 degrees at 30 knots and a temperature of minus 8 Celsius.