The hypothalamus regulates core body temperature through internal and skin thermometers, engaging behavioral and physiological responses to maintain homeostasis.

“it's the part of the brain that regulates body temperature and there's a thermostat in there and effectively a thermostat and thermometers there are thermometers that measure your core temperature there are thermometers on your skin that measure future threats to your core temperature like if you jump into a cold lake your core temperature doesn't instantly drop but your brain knows that it will drop because of the temperature sensors in your skin and so it can respond adaptively and then that system in the hypothalamus engages a behavioral a suite of behavioral and physiological responses to maintain temperature homeostasis”