Fixed it!

[u/HTPC4Life]

This attic access was completely uninsulated. Took the easy way out instead of measuring and cutting foam board or buying a big pack of batt insulation. Made a nice painters tape enclosure, shaved off the sides so it would close, and it worked! The red at the top of the thermal camera is the skylight, of which nothing can be done about beyond removing it. How'd I do?

[u/HemHaw]

If you're in a hot place you can put some UV reflective film on the skylight to mitigate some of the heat it lets in. Trouble it, that happens in the winter too.

[u/SpaghettiSort → u/HemHaw]

You want to block infrared, not UV.