WASHINGTON — It’s one of the iconic songs of Christmas, but the people who wrote it did so to trick themselves into cooling down on a sweltering summer day.

“The Christmas Song,” informally known as “Chestnuts Roasting on an Open Fire,” was written in 1945 by jazz singer Mel Torme and his writing partner, Bob Wells. Torme’s son, James, tells CBS News that Wells started the ball rolling. “Wells said, ‘Mel, I cannot cool down today, and I thought that if I could just [write] down a little wintry poetry, I may be able to trick myself,’” James Torme says.

They finished the song in about 40 minutes, James Torme says, and immediately brought it to Nat “King” Cole.

“And before they could get to the end, [Cole] said, ‘Stop! That’s MY song.’

“And it really was.”