Sound travels faster in warm air than in cold air. For example, sound travels 358 meters per second at 45 degrees Celsius, while it travels 330.4 meters per second at minus 1 degrees Celsius.
Since both sound and heat are forms of kinetic energy, the level of heat directly affects the transmission of sound. This is because molecular motion is increased as heat is applied. Molecules that vibrate faster have an accelerating effect on any vibrating sound waves that are passing through the area. Other factors, such as humidity and barometric pressure, also affect the rate at which sound travels.