I have the S2 3g and the weather is updating like normal. Initially, I set up the weather to show for a specific city, and it updated fine. Then, I deleted that city and just have it set to Auto based on location, and it's updating fine. Set to update every hour, and appears to be doing so. I did change my location settings to high, but I'm going to go back to Power Saving and see how that works.
A couple things to think about, if it's not working.
1) If you are using anything like Greenify, Shutapp, Doze, or something similar: Make sure that all Gear apps (Samsung Gear, Gear Plugin, svoiceprovider, Host Manager, Gear Module) are not included in the list of items to auto close.
2) If you are using auto location, try configuring just for a specific city, instead of using location services to update the weather location.
3) Weather updating likely only works correctly on Samsung phones, since it uses the built in weather service to TouchWiz (still works on Nova), and has nothing to do with any other Weather app installed on the phone. So, all configuration should be done in Gear Manager and/or the Weather Widget.