Wind The upper winds do not have major influence on airplane safety, but during the take-off and especially during landing they make a major safety impact. Besides the speed of the wind, another important characteristic is also wind speed variability i.e. the variation of the wind on temporal and spatial scale.
When wind is blowing from behind the aircraft on the runway (so called “tailwind”), it increases the relative velocity of the aircraft relative to the ground, thus making the landing/taking off distance longer. Therefore airplanes require longer runway and, whenever possible, taking off and landing are performed against the wind.
Crosswind, i.e. the wind hat has a perpendicular component to the runway is even more dangerous than the tailwind. It can cause the plane to be skewed relative to the runway, therefore it has to maneuver in order to keep its direction. Sudden gusts of crosswind while the airplane is above the runway are especially dangerous.  

Because of the abovementioned reasons, whenever the geographical position permits, runways should be constructed to be aligned with the prevailing winds on particular location. Unfortunately, this could not be done on Dubrovnik and Rijeka airports, where runways are perpendicular to bora, which causes major problems as well as temporary closures of these airports during the strong bora.