Temperate means mild, moderate. If you're a temperate person, you are calm, reasonable. If you live in a temperate climate, it's warm and sunny, but not too hot.
Like other words that sound similar, temperate has to do with measurement and range. Temperatures measure how hot and cold things are and someone with a temper is hot-headed or intemperate, the opposite of this word. A temperate person's life motto is summed up by Goldilocks: not too hot and not too cold, just right.