A jailbreak tweak called Forecast presents a handy weather widget on your iPhone’s lock screen for displaying current weather and the weekly forecast. Powered by Apple’s own Weather app, Forecast replaces the standard time and date at the top of your iPhone’s lock screen. Weather info is displayed on the right while the time is still displayed on the top left of the lock screen, giving you the best of both worlds.
Forecast Presents Handy Weather Info On Your iPhone’s Lock Screen [Jailbreak]