If the answer is yes, then the chances are that you need to fit a weatherproof socket to the exterior of your building. You may think that it is adequate to simply run a power cable through the window to outside and that this will be perfectly safe, however have you considered when it is raining heavily that water could run back down the cable to the socket inside and potentially cause a short circuit or the risk of electrocution?
In addition it may well be your internal power circuit does not have any form of Residual Current Detection (RCD) protection fitted to it, although all new modern houses and flats do require the fitment of RCD's not all older houses and factories do have this electrical protection fitted to their circuit's. In general however all external power circuits typically have RCD's fitted to them, this is because most often external equipment being used from the sockets are items like hedge trimmers and lawnmowers where there is actually a high risk of cutting through the electrical cable used to power them, and with an RCD fitted if this happens it cuts the power out in milliseconds before the user is even aware that cable has been cut through and safely prevents any risk of electrocution.
The key reason to use weatherproof sockets is that they are specifically designed to be weatherproof and water resistant and are IP rated and will offer various different levels of IP rating such as IP44, 55 & 66. Dependant on the IP rating it will depend upon whether the socket is designed to just be weatherproof when not in use, or to actually be able to be used whilst it is raining, as an example, and still remain impervious to the weather and remain electrically safe. Obviously the weatherproof sockets increase in price the higher the IP rating that they are, however the higher the IP rating the more electrically safe they are.
It is however obviously a good idea to go for the highest IP rated socket that you can afford to provide maximum electrical safety to you, or your workers, as the cost of any fatal accident can far outweigh the cost of the few pounds saved on the purchase of a cheaper socket.