Nobody can advise you with any confidence. These places are at altitude, and weather is wildly erratic. I was there in early to October one year, and it was 20 C under brilliant sun. It could just as easily been snowing. Be prepared with layers in case of cold conditions, but hope for perfect. You don't need to pack a parka just in case. Wearing your base layer, long sleeve, fleece, and rain jacket all at once, you will be fine.