I have weather elements on my iPhone 4 and it works great. Below is a screen shot. It is still a work in progress as the guys working on it are always looking to add new things like animations, etc.
Image
There is even a Cydia repo for it. Just add the below to Cydia. You will find HD and non HD versions in the repo.
http://brandon28139.exofire.net/repo/
Here is the link to the discussion at MacThemes on it.
http://macthemes.net/forum/viewtopic.php?id=16793347
My recommendation is to load the versions through Cydia as there have been many variations and some of them have some issues. Read the thread as well as there is a web page where you configure your location and preferences. The thread will explain everything.
Enjoy.