I like Weather Underground for most things. The 10-day graph presents information in a way I find useful and easy to understand. However, for the weather right now I like AccuWeather's MinuteCast. It's eerily accurate. I use them to plan my runs on variable days, and I almost never get caught in the rain if they say it's supposed to be clear. On the other hand, if it says it's going to rain in 23 minutes and I decide to wait for a bit, it practically always does rain in exactly 23 minutes. Ditto for snow in the winter. The exact amounts might be off, but the timing is usually spot on.