To survive in heat zones, you will need to improve your heat resistance. You can do this by finding yourself a suit of heat armor. To do this, you will need to head on over to Pingdish 6k and solve your usual satellite and rotation puzzle.
After this, you will learn of a location called Bangshelter 6L, so head over there now, but be ready to clear a dungeon full of enemies. There will also be enemies on the outside and inside of the bunker, and when you clear them all, head inside to find the Heat suit. Inside the bunker, you will find the Heat suit inside a container at the end of the bunker, along with some Superb loot along the way.
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The Heat suit is made up of three parts, and when all are equipped, they will provide you will a heat resistance of 145 percent, not too shabby! However, you don't need this much resistance, so you can easily mix and match pieces with other armor to get more stats and resistance.
You can also always increase your heat via crafting armor or upgrading it, along with using bio points, but we prefer the armor route as it saves bio points for mutations.