Thermokinesis is the ability to make something hot or cold. Those more adept with this ability can affect very specific areas of objects.
Danny’s ghost rays are also shown as having melting abilities as in Reign Storm, his ghost rays melted Dash's shoes without knocking him over. Later in The Fright Before Christmas, Danny’s ghost rays melted the pieces of paper of the Ghost Writer poem he apparently worked for decades on.
Vortex’s weather-controlling powers allow him to either alter the temperature of any given environment, like to heat objects until they combust or melt or even cool objects until they freeze or shatter. Vortex's duplicates engulfed themselves with one being heat and the other being cold and went in separate directions. Earlier in Vlad office, he also manifest his heat powers as heat vision that can easily melt his own snowman he created.
The Pandora’s Box allowed the Box Ghost to fire red-colored ghost rays form his eyes as heat vision. When the Box Ghost and his Ghost Pegasus were encased in ice by Danny's ice vision, the box emits heat to melt the ice, thus freeing them.