Now Wind
Now wind is the most current wind observation at an aerodrome — the instantaneous wind being reported at that moment, as opposed to a forecast or average. It is available through ATIS, AWOS, and direct ATC communication, and is most relevant for runway selection and crosswind component calculation at the time of landing or take-off.
Wind Variability
Surface winds are frequently variable in direction and speed. ATIS reports represent an average; the now wind from the tower or AWOS may differ. On final approach, the wind may shift significantly from what was reported. This is why monitoring the AWOS or requesting a current wind from the tower before landing, especially in frontal or convective conditions, is good practice.