Pre-requisites (USER ACTION REQUIRE):

1)  Stream_Weather_2_<GUID>.dat file must be available at: %userprofile%\AppData\Local\Microsoft\Outlook\RoamCache

1.1)  Create it manually by, Clicking on a little drop-down button in the Weather Bar and Add another city. Then change it back to the one you want.

Set Temperature Unit via GPO using PolicyPak Scripts Manager:

You will be able to set Celsius as default temperature (as shown in following screenshot), instead of Fahrenheit.

Temperature unit information appears to be controlled via Stream_Weather_2_<unique-guid>.dat file at this location: %userprofile%\AppData\Local\Microsoft\Outlook\RoamCache

We can change the DegreeType to 9-1 to convert it to Celsius. But as filename has a unique GUID for each user so please follow these steps to apply the change via PowerShell Script using PolicyPak Scripts Manager.

1. Right-click and Add Policy for PolicyPak Scripts Manager under User Configuration

   

2. Click Next on the Wizard and Select PowerShell script from the drop-down. Insert the following script. Then select both checkboxes, Run script as user and With elevated rights.

   $Path = "$env:USERPROFILE\AppData\Local\Microsoft\Outlook\RoamCache\*"
   $FileName = (Get-Item -Path $Path -Filter "Stream_Weather*.dat").FullName
   $Content = Get-Content -path $FileName
   Stop-Process -Name outlook -Force -ErrorAction SilentlyContinue
   Set-Content $FileName $content.Replace("DegreeType"" v=""9-1""", "DegreeType"" v=""9-0""")

   

   TIP: Outlook has to be closed to make this change, so be sure to add the "stop-process" line before the "set-content".

3. Finally, select an option to apply Once or when forced, and complete the remaining steps on the wizard.