Forecast for iOS7 is completely new and rewritten to support the clean look of iOS7. Forecast adds animated lockscreen and homescreen wallpapers showing the current weather conditions for either your current location or the first location in the default weather app.
The lockscreen also includes the current weather details (temperature, condition and high and low for the day). Swipe to the right to see the full forecast on a separate lockscreen page.
You can purchase Forecast from the Cydia Store for $0.99.