Almost any furniture can be used outside, provided it is protected from the elements. Since you are repainting them with exterior paint, you can use them outside too. Use at least two coats for best result.

Hello mazelady! Leenamark is right, you should be fine as long as you make sure you put on two or thee coats. Another thing you can do to prolong its life is to keep an eye on the weather and if it is suppose to storm really hard just bring them in real quick. You would be amazed how much just doing this for those big summer storms will prolong the life of any patio furniture! Another option is to go out and buy a cover for them, those also work wonders! Hope this helps!