Mother Nature!!! ‘A tornado leveled a house 2 blocks away and my antenna was fine!!!’And the opposite applies. Point being what force an antenna accurately sustains in most cases short of an extremely localized (like mounted to the mast) quality measuring instrument, is just a guess. Only remember 2 high wind storms coming through since mine has been up. Only thing I noticed is my guy wires loosened up a little. Eye bolts I used bent a little bit. My fault I used what I had on hand at the time. No idea what the wind speed was.