Forecast 2.1 for Mac can be downloaded from our website for free.
From the developer:
Forecast (was SimplyWeather) simply puts the weather in your menu bar. Just glance up and you'll see the current temperature outside. Click on it to get a more detailed view of what the current conditions are and what the next four days will be. Hover your mouse over the information to get a quick forecast of today or the next four days.
You may want to check out more Mac applications, such as Forecast Bar, Pro-Football Forecast or Weather Dock, which might be similar to Forecast.