I'll give you the step by step.
First, go to weather. Hit "real world weather(updated or static)" and then hit ok. Then, go back into the weather screen and click on "user-defined weather". Now, click on advanced. From this window you can click on each individual weather station.
IMPORTANT: Make sure to hit "cancel, cancel" on your way out, or else you'll have to go back in and click on real world weather all over again.
Hope that clears things up
