While the climate on the surface of Mars is pretty much completely dry, it's still possible that, every so often, it snows on Mars. These hellish storms would move at hurricane speeds and dump four inches of snow every hour
Mineral evidence collected on Mars suggests that small lakes do occasionally form on Mars. This hasn't happened often during the Martian drought, which has lasted for 3.5 billion years or so, but it appears these lakes form when meteorite impacts warm up ice in the planet's crust and forces them through cracks up to the surface, resulting in short-lived crater lakes.
The thing is, even a very tiny lake would have a massive effect on the entire planet because Mars's atmosphere is so thin. That's what UC Berkeley researcher Edwin Kite and his team found when they modeled Mars's current climate conditions and then added a single 50 mile wide lake around the equator. In the simulations the heat given off by this tiny lake threw the entire planet's atmosphere into a frenzy, issuing forth a column of warm, moist air traveling at 120 miles per hour.
Here's where things get interesting. As the furious plume began to freeze into ice, the storm cloud that formed extended up to 20 miles high. By contrast, Earth storm clouds only reach up about 12 miles because the ozone layer heats the upper atmosphere and dissipates the clouds. And when it starts snowing, you'd be faced with a storm with close to hurricane speeds, dumping levels of snow rarely seen in even the most extreme blizzards on Earth.
Team member Scot Rafkin of the Southwest Research Institute describes the scene:
"Imagine being in the most severe thunderstorm you've been in, where it's really dark and ominous-looking. Then make it darker and more ominous, with snow coming down at an unbelievable blizzard-like rate."
Once the snow had finished falling, it would likely remain on Mars for the foreseeable future, at least until the actual tilt of Mars's orbit changed - something that's thought to occasionally happen due to neighboring Jupiter's immense gravity. This would leave behind water-formed minerals in the general vicinity of the temporary lakes. So then, while Mars's climate may appear unchanging, every so often it can quite violently prove that wrong.
Journal of Geophysical Research by New Scientist. Artist's conception of a Martian crater lake via.