Definition
The temperature of the air measured at or near ground level, typically recorded by weather instruments at a standard height above the ground at an airport or weather station.
Plain English
How warm or cold the air is right at ground level, where the airplane sits before takeoff.
Context Anchor
Seen in weather, atmospheric pressure, and aircraft performance discussions, especially when comparing conditions at the ground with conditions aloft.
Why Pilots Care
It directly changes air density and therefore takeoff distance, climb rate, and engine performance.
Grounding Statement
On a hot ramp, the air near the ground can make the airplane perform as if the airport were higher than its actual elevation.
Intuition Check
Surface temperature does not mean the temperature of the runway pavement or the airplane’s skin. In this context, it means the temperature of the air near the Earth’s surface.
Example Sentence 1
With a surface temperature of 35°C and a high field elevation, the pilot calculated a density altitude well above the airport's actual elevation.
Example Sentence 2
Before departure the pilot checked the surface temperature to adjust the mixture and confirm performance numbers.