A warm glow is a sensible result of a good spanking.
Spanking results not only in pain but also has the well-known effect of reddening the skin. This is caused by an expansion of blood vessels. The reddening is not only visible, but also sensible as the spanked area will be warm (or even "hot") to touch. This is not only a subjective impression: the skin actually has a higher temperature than normal, although the temperature is no higher than the body temperature of 36 Celsius — the impression that it is "hot" is therefore an illusion, you could never "fry an egg on a hot bottom". It is the expanded blood vessels that cause the higher temperature, not the other way round.
The spanker or a third person can easily feel the warm glow with his or her hand, while the spankee typically doesn't feel it in their bottom until several minutes after the spanking has ended and the acute pain has faded. The real "warm glow" sensation, thus, comes circa 15 or 30 minutes later. Depending on the circumstances it can be felt for up to several hours. If the spanking has been severe, during this period the warm glow is often accompanied by waves of itching.
References to the warm glow in spanking art
Spanking is sometimes called "bottom warming".
The warm glow is often mentioned in spanking literature, both fiction and nonfiction, and is often described as a not unpleasant sensation, up to the point where it makes the spankee feel "nice and toasty". The warm glow effect seems to be felt best either when the spankee is put in corner time after a spanking, or tucked into bed.
Collegeboy has made a reference to it in one of his F/m spanking drawings, with a red-bottomed boy in pajamas smiling "There's nothing like a warm bottom on a cold night, courtesy of Mom." (see right)