I find that whenever I am actively engaged in magical practice, moving energies through my various energy centers, I naturally heat up in the process, often needing to shed multiple layers of clothing. That's true whether I am inviting desired outside energies into me, blocking unwanted outside energies from coming in, or clearing out unwanted energies from within.

It doesn't seem to be the addition or subtraction of outside energies that makes the difference, so much as the opening and activating of my own energy centers. Of course, many of the energy centers act as portals between the planes, so opening them naturally allows energies to spill back and forth. That warming effect is the same from prayer, ritual, incantation, vision work, scrying, and healing.

Once I begin moving energies through my energy channels on any of the planes, my physical body begins heating up. The only exception is that sometimes while combating a potent magical attack (whether coming from inside or outside) I will get significantly chilled. I assume that that chilling comes from the attacker trying to block my ability to channel energies. Once the attacker relents, I go right back to overheating again and have to throw off all of the extra clothes I put on.

— Christophe