From down here on Earth, it’s easy to imagine Mars like a rocky Sahara Desert: hot, sandy, and relatively calm. You may be right about the sand, but Mars’ weather is nothing like we experience on Earth. Although Mars’ atmosphere is made mostly of carbon dioxide, it is so thin the greenhouse effect on Mars is almost nonexistent. As such, Mars is on average a chilly negative 50°C. And without an atmosphere, UV rays hit Mars’s surface directly. You can enjoy hypothermia and a sunburn all at once!
Mars also enjoys different seasons throughout its orbit, but because its orbit is so elliptical, the tilt of the planet also affects the seasons. The southern hemisphere is closer to the Sun during its summer and much, much farther away during its winter, so it has more extreme seasons than the northern hemisphere. During winter on the northern and southern poles, temperatures drop so low (think negative 130°C) that the carbon dioxide turns into dry ice.
In addition to the chill and extreme seasons, Mars has strong winds from the cycling of carbon dioxide gas. These winds create heavy dust storms that can obscure large patches of Mars’ surface, even the whole planet. Additionally, Martian winds whip up dust devils, tornados that rise up from the ground instead of the sky. Between the dust storms and dust devils, Mars’ atmosphere is perpetually filled with dust, giving the sky a yellow-brown color. Without the dust, Mars’ atmosphere is so thin that the sky would appear as black as, well, space!