Okay kiddo, "tennōki" is a Japanese word that means "weather forecast." You know how sometimes you look outside and it's sunny, and other times it's rainy? Well, tennōki is a way for grown-ups to predict what the weather will be like in the future, like tomorrow or next week. They have special tools and machines that measure things like temperature and wind speed, and then they use that information to make a guess about what the weather will be like. So if you're planning to go play outside, you can check the tennōki to see if you should wear a coat, bring an umbrella, or maybe just wear a T-shirt!