Comment on System.Monitor.HUD by Huggi9
Both Afterburner (for Intel CPU) and CoreTemp (for AMD CPU) can report temps in Fahrenheit. You'd then need to edit one file to change the display from °C to °F.
Afterburner - open "Settings" > "User Interface" tab > change "Temperature Format" to Fahrenheit.
CoreTemp - open "Settings" > "Display" tab > tick "Display temperatures in Fahrenheit".
Now, open "Documents\Rainmeter\Skins\System.Monitor.HUD\Resources\MeterMeasure\CPU.inc" in Notepad then edit the very last line (change the C to a F). Save, exit, and refresh Rainmeter.
Afterburner - open "Settings" > "User Interface" tab > change "Temperature Format" to Fahrenheit.
CoreTemp - open "Settings" > "Display" tab > tick "Display temperatures in Fahrenheit".
Now, open "Documents\Rainmeter\Skins\System.Monitor.HUD\Resources\MeterMeasure\CPU.inc" in Notepad then edit the very last line (change the C to a F). Save, exit, and refresh Rainmeter.