Clear Sky Chart is a site developed by Allan Rahill and heavily used by astronomers as a weather forecast. We mostly look at the cloud cover percentage in order to predict what the weather will be like for observing.
You can see the hover text and what the symbols mean by clicking the image, which will redirect you to the site.
If the image does not redirect you to the site, you can clickhere. Also, the image should update when the site is updated. Look at the date in the top left corner to be sure it is accurate!