It is also quite possible Mars still has 'hot spots' as geologically it was very 'recently' volcanically active. Every now and then there's little anomalies that possibly hint at subsurface hot spots that might allow for hot springs and similar.

In Robert Zubrin's fictional (but hard-science) book "First Landing" on the first manned Mars mission they actually find a hot spot and drill into it resulting in a geyser (which obviously, the water instantly freezes creating a snow-like effect). All of Zubrin's books are worth reading if you are at all interested in manned missions to Mars. He has some non-fiction looks (that are a bit outdated now due to scientific discoveries, like finding the polar caps are lousy with water ice) but he goes into the math and gets you in the right mindset. The fiction book is similar in nature to The Martian (came out well before The Martian) and he also has a short little fiction book meant to be sold to future colonists called 'How to Live on Mars: A Trusty Guidebook to Surviving and Thriving on the Red Planet' which also takes a hard-science fiction approach to the subject.