Hi Charles,
You would need a Weather API to display something like that in your website. Perhaps this article might assist you: https://www.wpbeginner.com/plugins/how-to-show-weather-forecast-in-your-wordpress/#:~:text=To%20do%20that%2C%20simply%20navigate,on%20the%20API%20Keys%20tab.
The effect of the Weather API on your website depends on the API itself. It would only be a bad idea if it badly affects your site’s performance.
Hope this clarifies!