Scattered strong to severe thunderstorms are expected today across the Mid-Atlantic and forecast to contain heavy to excessive rainfall. Numerous instances of flash flooding are possible in southern Virginia and north-central North Carolina. Severe thunderstorms are also possible across the northern Great Plains today. Elevated to Critical Fire Weather located across the Intermountain West. Read More >
Density Altitude: The altitude in the standard atmosphere at which the air has the same density as the air at the point in question. An aircraft will have the same performance characteristics as it would have in standard atmosphere at this altitude.
High Density Altitude: A condition of the atmosphere that reduces an aircraft’s performance capability to below a level of standard performance at a specified altitude.
Cold, Dry Day![]() Low Density Altitude |
Hot, Humid Day![]() High Density Altitude |
Air density is determined by Pressure, Temperature, and Humidity.
On a hot, muggy day, the air becomes "thinner" or less dense, and its density at a pilot's location is equivalent to a higher altitude in the standard atmosphere. Thus the term "high density altitude."
Pilots must determine if high density altitude will impact their flight by calculating density altitude and checking their aircraft performance charts.