You acting like is only Jamaica hot lol. The 33 - 35c days here in summer is brutal. Then when I turn the pc on in the house gets even hotter.
Thankfully summer is now over though.
For installs you definitely need internal. Some programs will allow you to install on externals though.
I made one of my drives external (bought an enclosure) for the simple fact that when my pc was down I couldnt get stuff off the drive.
Now that it is usb i can plug it in my laptop etc.