There are times when libraries wish to have their wifi signals available to the public outside of the building. This is even more the case during the Covid pandemic when branches have had to shut their doors and yet wish to continue playing the critical role of providing Internet access. But even beyond Coivd, there are scenarios like branches with outdoor seating areas, or branches in areas that have large seasonal vacation populations, that find having stronger Wifi signals outside of the building helpful to their patrons and the public.
While a certain amount of Wifi signal from access points inside the building may cary on outside the walls, an intentional approach to delivering Wifi service outside the building could employ WAPs that have been specifically constructed to withstand the elements. There are many offerings available (cf https://www.mbreviews.com/the-best-outdoor-access-points/) - one robust offering from Ubiquiti, the Bullet M2 stands out as being both affordable and durable.