Teak wood can stay out year round, but any wood exposed to the weather year round will become rough. You may find yourself sanding it every year, at least the parts that you touch. If you use the furniture a
*lot*, use will keep it smooth.
Teak is not the only wood that can stand up to staying out. Cedar and redwood hold up too, and cedar costs less.
Garden furniture made of durable wood like teak and cedar does not need to be protected with paint or urethane deck stains. Once a protectant is used, though, it generally needs to be touched up every year because it flakes and that looks and feels really bad and can make quite a mess.
Garden furniture that has to stay out all year needs stainless steel or brass fasteners, preferably nut and bolt fasteners not wood screws.
I have some plastic garden chairs that I found at a charity shop years ago, bought as a temporary measure while I looked out for "good" garden furniture. I still have the plastic chairs, and like them. I like to move them around, something that can be a big hassle with heavy wooden furniture.
Do you need all-weather garden furniture? Are you going to be out in the garden in winter? Or is it that you have nowhere to store the furniture over winter? Do you even need garden furniture? Wait and see...
Una