This was written by the lyricist Sammy Cahn and the Broadway songwriter Jule Styne in 1945. It was first recorded by Vaughn Monroe, and has since become a standard, with Patsy Cline, Martina McBride, Garth Brooks, Herb Alpert, Chris Isaak, the Carpenters, Carly Simon and Jessica Simpson just some of the artists to record it.

Dean Martin's version is one of the best known, and it fit his image as a swinging member of the Rat Pack without a care in the world.

The most popular version on American radio (according to ASCAP), is by Harry Connick Jr.

Although this song is associated with Christmas, there is no mention of the holiday in the lyrics. It's about making the most of a snowy day by spending it with a loved one by the fire.

In the book Songwriters on Songwriting by Paul Zollo, Sammy Cahn said: "'Let It Snow' was written on Hollywood and Vine on the hottest day of the year. I said to Jule Stein, 'Why don't we go down to the beach and cool off?' He said, 'Why don't we stay here and write a winter song.' I went to the typewriter. 'Oh the weather outside is frightful, but the fire is so delightful, and since we've got no place to go, let it snow, let it snow, let it snow.' Now why three 'let it snow's'? Why not two or four? Because three is lyric."

A version by Rod Stewart recorded for his 2012 holiday album, Merry Christmas, Baby, reached #1 on Billboard's adult contemporary chart.
In December 2018, Martin's version entered the Hot 100 at #49 and peaked at #20 the following month. It was the late singer's first hit on the tally in nearly 50 years, with the last being "I Take a Lot of Pride in What I Am," which landed at #75 in 1969.

On November 13, 2019, an official music video was released. In the animated clip, Dean Martin and his family host a Christmas gathering in their cozy cabin, where Santa shows up to distribute gifts while they're sleeping. Only two children are depicted in the video, but in reality Martin had seven biological children and one adopted daughter.
This was the most-searched song on Google in 2011, not because it was suddenly popular, but because Google created an Easter Egg around it. When you typed "Let It Snow" into the search bar, snow would cascade down the screen.