Why are steam burns so severe?

Large stores of energy are required for liquid to transform into gas, and this energy is released all at once when steam hits the skin and transforms back into a liquid. This results in a burn more severe than one caused by water of equivalent temperature, says UCSB ScienceLine.

A steam burn can cause more damage than boiling water of the same temperature. When boiling water makes contact with the skin, it decreases in temperature but does not undergo a phase change like steam, states the University of British Columbia. Steam decreases in temperature as it hits the skin, condensing into liquid and undergoing a phase change. This change releases energy quickly enough to damage skin cells more severely than boiling water, even when the water is the same temperature as the steam.