Today's Image of Mars shows clouds in The Red Planet's North Polar Region obscuring the view of Mars Odyssey's THEMIS. Some of the lower portion of this image is entirely shrouded by clouds, so much so that THEMIS can't even make out the surface.
Clouds on Mars are generally 10-15km above the surface and primarily made up ofsublimated carbon dioxide ice. Occasionally the clouds will be made up of tiny water particles. That doesn't mean it rains on Mars though!
Mars is so cold that it couldn't rain, but scientists speculate that it does snow! Scientists have only seen snow fall in the upper atmosphere a few times and have no evidence that it ever reaches the surface, but who knows! Maybe it only happens every so often, like a leap year every four years! (See how I worked that in there? Don't worry, you can hold your applause!)
Clicking on this image will take you to the high resolution image from THEMIS. [See Universe Today's caption for a subimage of this one]