I would say, it would be more like 105 down to the teens. I would design for 100 degrees. Even here in the sub tropics we need to deal with 85 degrees or so (in the shade)and it never freezes here. Direct sunlight will add at least 20 more degrees, particularly over a solid surface like a roof, concrete slab, masonry wall etc.
PVC may be the worst for expansion rate and it will pull apart if it is too tight. That "droop" may be a good thing if it is hot. I went with EMT in my screen cage just for that reason but it is not really an option on a boat dock here because it will rust out right away. YMMV on a freshwater lake but it is still just a matter of time.
