This planet has a great quantity of carbon dioxide in its atmosphere and a bit of nitrogen, creating a severe greenhouse effect. With more proximity to the Sun than Earth and the mentioned effect, Venus experiences extreme high temperatures near 500ºC.
Strong winds of 350 km/h or more seem a consequence of pressure and temperature differences in several layers of the atmosphere. That kind of atmospheric phenomenon increases dangers to potential life there; in fact, almost all experts don't believe that this planet might have life.
Then, it has an atmosphere that doesn't allow a single organism, and that's principally due to the greenhouse effect. Without this effect, Venus could have a temperature similar to the Earth...
However, right now, its temperature never falls from 400ºC. That's an incredible setup, hotter than some industrial ovens, able to melt metals like tin, plumb and others. No human could resist more than a few seconds in that extreme temperature. Even spaceships or robotic explorers would expect multiple dangers and an increased degree of catastrophic failure.
An interesting fact about Venus is that one complete rotation, a day on Earth, lasts more than two hundred days. It's still unknown the reason for it!