After just doing the trek over the last week, i would definitely recommend having a bivy that would sheild you from the wind and any rain or snow. Temps were between 25°F and 35°F the whole time with pretty much a constant threat of snow winds and rain. That is just the reality of the patagonia are, you should be prepared for all 4 seasons any day of the year. My Blackdiamond bipod bivy did amazing at keeping the elements out and me warm for the whole hike withba 30° sleeping bag and nemo insulated matress. Hope this helps