Dragonspine's cold climate and the sheer cold mechanic are a hurdle while exploring near the water bodies as your chance to freeze increases. From the conversations with Iris, you know that you should always look out for heat sources, whether it's seelies, heat beacons, or fire torches. Any heat source can reduce your sheer cold accumulation and save you from HP loss while exploring.  On top of that, make sure you have plenty of recovery food and attack-boosting dishes because enemies in the Dragonspine area may be difficult for you. I cook plenty of sweet madame most of the time before venturing into an unknown region and consume it periodically if I get into a tough fight. If you want to avoid excessive sheer cold, you should have a pyro character in your team. Having a pyro character in your teams like Amber or Bennett will help you to light up torches and be around a heat source.