I hope this is not a late response, but will post it to make sure everyone else that runs in the same problem
After almost a year , the same problem exists. I have opened a ticket with Premier Support to find that the problem is a known issue and you can not change it from Celsius to Fahrenheit with GPO's it needs to be change locally from the File Menu .
User Policy > Admin Templates > Microsoft Office 2013 > Outlook Options > Preferences > Calendar Options > Weather Service URL
- Enable the policy and set the url to:
http://weather.service.msn.com/data.aspx?weasearchstr=calgary&weadegreetype=C&src=outlook
This will still show the weather in Fahrenheit !!