WeatherSimple is a weather app that runs on your menubar. By default, its icon shows the current temperature. If you click on the menu, you will access a window that displays some more information. This window shows the name of the location that you have added, the wind speed and direction, the humidity percentage, and overall weather state (cloudy, clear, etc), along with a four-day forecast with state, maximum temperatures and minimum temperatures.
When I first ran this application, it displayed a temperature of -460 degrees. I quickly realized that the app didn't even try to locate where I am, so this wrong temperature meant that no cities were added. This was quickly solved by adding a city manually. All I did was type the name of the city I was in and clicked on "Save". The app recognized the name and displayed weather information right away. The data seemed to be accurate, but I realized that the app doesn't seem to update the temperature automatically, because when I added another city (you can add up to 3), the temperature increased 3 degrees celsius.
In short, WeatherSimple works mostly well. They could solve that wrong -460 degree temperature error when there aren't cities loaded and they could improve the updating. But if you are looking for a simple weather application, this can do the job.