I also use weawow ... with darksky as the provider. The other providers (at least the free ones) seem far less accurate (for Seattle anyway).

I've started using willyweather for higher-fidelity UV data, and its forecasts (from NOAA) seem reasonable and I like the forecast-vs-actual graph. Though the UI requires some extra clicks to get all the info that weawow manages to get onto a single user-friendly page. (First-world problems....)