Here is a weather report you would never expect to see on Earth: partly cloudy with a chance of "rocket" dust storms.
Dust is a major player in Martian weather, and in fact there have been times when the entire planet has been covered in dust. There are dust devils (like on Earth) and photographs have been taken of lightning in the dust storms. But the other day I came across a new term that I had never heard before: "rocket" dust storms.
Some scientists have created computer models to try and simulate what is happening on the surface, and the belief is that "pockets of dust" inside a storm may become heated by the sun and "rocket" their way towards the upper parts of the atmosphere. The speed of ascent is up to 100X faster than Earth-based storms. The closest analogy could be a rapidly-rising cumulonimbus cloud here on Earth on a summer day, although those climb at a much slower pace.
It also appears there is a lot of lightning with these storms. Although the genesis of lightning in dust storms is not fully understood, this could have implications for future settlements and missions. The Martian atmosphere is also mostly carbon dioxide and much thinner than the lower levels here on Earth. The thinner atmosphere, lower gravity, and finer dust particles could explain the rapid ascent.
Another oddity I recently read about is "sand geysers". These occur in the southern polar regions of Mars and typically are associated with a spring thaw. "Thaw" is a relative word here because the ice on Mars is mostly frozen carbon dioxide. The formation of these geysers is poorly understood, but basically a jet of heated carbon dioxide erupts from the ice sending dust and ice rocketing skyward. Accompanying these geysers are often dark spots and spider-like patterns in the ice.
What does all of this mean for future settlements and exploration?
It means that exploration of the southern ice cap in the spring (via a buggy or other vehicle) might be a bad idea...considering that the geysers may theoretically reach speeds of up to 100 mph. The planet wide dust storms, though, pose a unique challenge. Unless the planet is somehow terraformed, a lot of projects/services/missions that involve people could be temporarily suspended until the storm passes. Depending on how dense the clouds get, finding shelter might be the best bet since visibility could become a significant problem.