The only major resource I can find on the subject is The History of the Snowmen by Bob Eckstein. In it, he comments that the earliest mention of an anthropomorphic snow sculpture is from an illustrated manuscript, The Book of Hours, from the Netherlands. It depicts a snowman with a rather anti-Semitic nature, lacking arms and legs.

Eckstein makes mention of a more detailed event in history from Brussels, known as the Miracle of 1511, which was a public art instillation of over 100 snowmen built by the townsfolk. Many of them were politically-themed, some shown making rude gestures toward the church or government buildings. Others were comical, while others yet had some severe lewd connotations.

Source: Winter's Effigies: The Deviant History of the Snowman