1) Open the Weather Gadget and position it in the upper right corner of your screen. Setup any settings you might want like zip code, opacity, Gadget size, etc.
2) Copy the following file to your deployment share:
3) Setup Computer Group Policy Files Preference similar to the below screen capture. The file will be copied to the default users profile and therefor any new user will get the Weather Gadget on their desktop along with the proper settings.
TIP: GPP Files will create any folders in the destination path that do not exist. There is no need to create missing folders.
Source: \\MySCCMServer\Packages\Windows Deployment Files\Settings.ini
Destination: %SYSTEMDRIVE%\Users\Default\AppData\Local\Microsoft\Windows Sidebar\Settings.ini