If your Sim is wealthy buy a Styling Station or go to the Salon and pick and chose the outer wear you want for different weathers and occasions, there is a little plus sign which allows you to add as many outfits as you want then when you click "Change Outfit" on your Sim just select the appropriate garments from the outer wear list. You will find that it makes quite a lot more washing changing clothes indoors, but doing it outside in the garden or away from home minimises the laundry.
