Redirect where ArcGIS Pro writes temporary or scratch files during processing

Summary

Note: 
This capability was introduced at ArcGIS Pro 3.1 - versions 3.0 and earlier do not possess this functionality.

Starting at version 3.1, ArcGIS Pro can now take advantage of the ARCTMPDIR Environment Variable, a mechanism which can be used to redirect where certain temporary and scratch files are stored on a file system.

Below are some examples of what types of files and/or processes will adhere to the implementation of an ARCTMPDIR Environment Variable if it iss present on a system:

• The "ArcGISProTemp<PID>" folder, which is temporarily written to-disk when new Projects and/or Blank Project templates are created but have not yet been saved
• Geoprocessing Tools that utilize the TopoEngine.
• New Python Jupyter Notebooks

Note: 
Not all temporary files ArcGIS Pro generates during usage will adhere to the implementation of ARCTMPDIR.

1. Path specified in ARCTMPDIR Environment Variable
2. If not present (or invalid), the %TMP% Environment Variable
3. If not present (or invalid), the %TEMP% Environment Variable
4. If not present (or invalid), the default Windows User Profile Location

Procedure

1. Navigate to Start > Windows System > Control Panel > System. Click the Advanced system settings. This opens the System Properties window.
2. Click the Advanced tab, and click the Environment Variables button in the bottom-right.
3. Under User variables for, click the New button and enter in the following: 

variable name: ARCTMPDIR
variable value: C:\temp

Note:
Replace C:\temp in the above with a disk location appropriate for the current user. The current user must have full read/write access to this location.

4. Click OK in the New System Variable dialog window, click OK in the Environment Variables dialog, and click OK on the System Properties dialog window.
5. Close ArcGIS Pro (assuming it was open), and log out of your Windows User account. After logging back in to your PC, this redirection should now be in effect.