Are tempfile directories eventually cleared by system

Are tempfile directories eventually cleared by system

I am doing some processing with scripts and are currently using a fixed
directory to do this file operations in. I want to use the tempfile
module's tempdir to do this in a more elegant way.
using following code:
import os
import tempfile
#define the location of 'mytemp' parent folder relative to the system temp
sysTemp = tempfile.gettempdir()
myTemp = os.path.join(sysTemp,'mytemp')
#You must make sure myTemp exists
if not os.path.exists(myTemp):
os.makedirs(myTemp)
on my mac it creates a folder in: /var/folders/nn/zyl78zb..... on pc it
creates a (hidden folder inside my user directory.
From tempfile module documentation I understand that if you create a
tempdir you have to clear it yourself. Sometimes I do want to go and look
at intermediary files so I do not want to automatically delete them. If I
leave them will the os eventually clean these directories (after reboot,
etc)? If I do not clean them directly from script, following runs could
likely get a different tempdir. This could eventually lead to large amount
of unused and unwanted files.
I have scoured the tempfile documentation, but cannot seem to find an
answer. It is probably more a OS question, but someone with tempfile
module experience should know.