Don't you sometimes wish that there is a short way to know the weather? It's now available with the new jailbreak tweak Forecast. Get it for $0.99 under the ModMyi repo. It requires iOS 5+
ForeCast allows you to have a whether widget on your lock screen instead of the clock. Don't worry, this does not remove the clock. You can still see the time and date on the left side of the screen.
Forecast allows you to set only one city. To select your city, go to your weather application. Place the city you want it to show at the top and you are good to go.