Some very tentative evidence that water exists today, but buried down about 500 meters below the surface but still causing new gullies to form. Possible evidence for an ocean at the north pole at one time. Possible evidence for rain falling on the oldest craters billions of years ago. Martian meteorites show evidence that they were formed in the presence of water. Currently wind and dust storms shape the surface of Mars.
Dust devils leave tracks, planet-wide dust storms, etc.
Coincide with times of maximum solar heating on the Martian surface. Winds can reach 100 mph. All those old volcanoes could have supplied enough carbon dioxide and water to enable the greenhouse effect to get running, making Mars warm enough to have liquid water. If Mars lost the carbon dioxide, lose greenhouse effect, water freezes or evaporates. Much to learn about it, more missions planned.