Meteogram is an amazingly customizable widget-type app that shows everything you could imagine on a timeline/chart. One of my all-time favorite and most used apps. It is updated regularly, and the amount of customization is insane. It is so nice to be able to just look at a chart and instantly know everything you need to know about the upcoming hour(s) and day(s).
I have been also been using an app called Forecaster which is pretty cool, that’s more of a conventional weather app.