Cold receptors begin to perceive cold feelings when the skin surface temperature falls below 95o F.
It is primarily activated when the skin's surface temperature is over 71oF and is no longer triggered when the skin's surface temperature falls below 41o F.
As a result, when submerged in cold water for extended periods of time, one's hands or feet begin to feel numb.
Hot skin receptors:
Hot receptors begin to perceive hot feelings when the skin's surface temperature increases over 86oF.
They are activated at 113oF.
Pain receptors dominate above this temperature to protect the skin and tissues beneath.