Hello Communitiy!
First I have to say sorry for eventually bad English. I'm from Germany.
I run Pi-hole on a Raspberry Pi 3 and my idle Temp is about ~48°C. This seems to be an normal temp. but Pi-hole shows a red logo which meens it's to high. Is there a possibility to change that alert-temp. for myself? Can you give me a hint in which file I find that temp.-limit?
Thx and greetings from Germany!
Don't apologize for your English skills - they are fine. We as developers of Pi-hole are widespread all over the world, so there is also the possibility to get a German answer here 
Die Temperatur ab der auf Rot umgeschaltet wird ist mit 45 Grad fest im Code verbaut. Das steht hier. Ich denke wir können die Temperatur anheben, aber ich werde das noch mit den anderen absprechen. Meine Raspberrys sind allesamt in Gehäusen verbaut und haben eine typische Temperatur rund um 52°C.
English:
The value from which on the temperature is fixed to 45°C (see here). We might consider adjusting the value since especially Raspberrys in case usually tend to have some temperature up to 55°C under normal conditions.
Where is this red logo for the high temperature?
I don't see it on the pihole admin page.
Dear DL6ER,
many many thanky for your quick answer! I searched a lot to fix this problem, but don't searched in german language.. my fault. Also thanks for opening a Github Pull request in order to fix this with upcoming releases!
Keep up your good work at Pi-hole! 
Just have a look to the picture I uploaded. It's the red flame before "temp"
That's strange, it simply isn't there on my admin page.
I am running Windows 7 with Firefox to look at the admin page.
I believe I have the very latest Web Interface Version v1.4.4.2, because I just did a re-install this past week.
Thats an very old version of the webinterface. The missing Status on the top left corner is a known bug in the previous release. So I think your update wasn't correct. Maybe a new install could help. The new Pi-hole version runs like charm! I highly recommend doing that step in order to get all the new and great features! 
Maybe uninstalling by typing "pihole uninstall" and installing it again with the known command could help you.
The current version for the web interface is v2.2.
Install it using
pihole -up
There is also the possibility that the temperature is not available (happens often when running on a virtual machine instead of some real hardware). In this case, there is nothing to display and hence, we don't show anything at all.
We can assist you in case you use a configuration where our current scripts cannot find the temperature although it is running on a bare metal server.