What does QNH indicate in a TAF?

QNH refers specifically to the altimeter setting adjusted to sea level pressure. In aviation, QNH is critical as it allows pilots to calibrate their altimeters to ensure that altitude readings correspond accurately to the actual altitude above sea level. This is essential for safe flight operations, especially during takeoff and landing phases when precise altitude measurement is crucial.

When interpreting a TAF (Terminal Aerodrome Forecast), QNH readings help pilots understand the atmospheric pressure conditions at an airport or aerodrome, which in turn influences their flight planning and approach to landing. Understanding QNH enables pilots to use correct altimeter settings, ensuring they maintain the required altitude relative to the geographical terrain.

Other options like wind speed, humidity level, and temperature, while relevant to aviation weather, do not specifically represent the altimeter setting function that QNH provides.