WeatherDock is an excellent desktop companion to follow the weather.
The application picks up the feeds from weather.com, which is widely considered as one of the best sources on the internet. You'll not only get 10 day forecasts and 2 day part info but also precise information such as real and feels like temperature, sky conditions, pressure, wind speed, humidity and UV. One little info it lacks though is predicted accumulation.
What I really like about WeatherDock though is the multiple display options. It can appear as a program window, a dock icon, a desktop icon or even a menu bar. The icons look really snazzy and are ideal to get a quick glance of the weather in your area. The menu bar is more discreet, but if you really want to dig into the details the best is to open up the program window.
If there was one drawback it's that WeatherDock only works with weather.com. It'd be great to be able to choose the weather feeds, as regional weather sites sometimes give out more precise information. On the whole though, weather.com is an excellent source, with detailed weather data.
WeatherDock is an excellent weather notifier for Mac with four different display modes, which shows advanced conditions from weather.com.