Three Christmas songs that do not mention Christmas?

'picture print by Currier and Ives' mentioned in Sleigh Ride

Several of the very best 'Christmas songs'  make no specific reference to the festival itself.

Let It Snow, Marshmallow World, Winter Wonderland & Sleigh Ride are idyllic evocations of winter in the north-east of the USA. They do not directly refer to Christmas

Jingle Bells (1857) was originally written for Thanksgiving under the name 'One Horse Open Sleigh'. The sleigh/Santa Clause association was planted in the public imagination and underlined by the more familiar title. Now the sound of jingling in the opening bar is one of the best known sonic symbols of Christmas.

Sleigh Ride feels like it has been with us forever but is comparatively recent. Leroy Anderson wrote the music during a heatwave in 1946 (Iriving Berlin was similarly inspired for White Christmas). The original version was an instrumental.
Mitchell Parish (better known for the words of Stardust)  added his lyric to Sleigh Ride in 1950. The song is now amongst the top ten most played pieces Christmas song across the world - and the most popular according to ASCAP survey of 2010.  

Sleigh Ride is also a staple of most primary school Christmas concerts - mercifully I Wish It Would be Christmas Every Day remains confined to shopping malls and office Christmas parties.

Winter Wonderland has a tragic origin story. It was initially written as a poem by Richard Smith, while he was being treated for tuberculosis in a sanatorium in Honesdale, Pennsylvania, and was inspired by looking out on mountain snow. Smith would only live another year, dying at the age of 34 in 1935.

Marshmallow World - in contras was written by a professional songwriter, Carl Sigman, in 1949 and only later adopted a Christmas song