windsocks have a max wind rating, i.e when it is horizontal it is showing x knots or above. I think 15kt and 25kt spring to mind, depending on the size.
From
FAA windsock specifications:
4.2.6 Windsock Extension. Test the windsock to assure that it extends fully when subjected
to a wind of 15 (+2,-1) knots (+3.7, -1.8) km/hr or (+2.3, -1.2 mph) ).