An inflation valve for use with an inflatable emergency evacuation slide includes a thermally actuated gas relief valve having an exhaust port the effective size of which increases with increasing temperature. The exhaust port is metered by a valve member. The valve member position is controlled by a thermal actuator that lengthens with increasing temperature. At high ambient temperatures, the valve member moves to uncover the exhaust port thereby increasing the effective size of the port so that a large percentage of the inflation gas is vented. At low ambient temperatures the valve member moves to cover the exhaust port, thereby decreasing effective size of the exhaust port so that little or no inflation gas is vented.