This has made the news recently:
Quote from the article:
The planets may also be tidally locked to their star, which means the same side of the planet is always facing the star, therefore each side is either perpetual day or night. This could mean they have weather patterns totally unlike those on Earth, such as strong winds blowing from the day side to the night side, and extreme temperature changes.
What I always wonder about such planets: wouldn’t water tend to flee the sunward side and migrate to the dark side? Any water that falls as snow on the dark side would tend to stay there, and thus, slowly, the sunlit side would become a parched desert and the dark side covered in glaciers? Or would sea currents manage to withstand freezing and keep up a circulation between the light and dark side?