Don't know about 'buses but Boeings usually have a max windspeed for operation of the doors and airstairs, which a prudent operator could take as a limit for the whole aircraft; no point taxying about if the doors can't be opened.. .. .Not many people know that there is also a design limit for the slides ( typically 25 knots), above which their correct operation is not assured. There are occasionally pictures of deployed slides having been blown back over the top of the fuselage etc. Yet amazingly (to me anyway) aircraft are allowed to operate in winds above the slide design speed, or conversely such slides are certificated for installation on aircraft where the aircraft is operated above the slide design speed. Limiting aircraft to 25 knot winds would be somewhat restrictive, so why aren't slides required to be improved?