What makes compact florescent lamp wear out so fast?
Filament lamps have a lot going for them. They can soldier on running at temperatures that would happily destroy the lamp fittings.

However, the electronic ballasts in CFLs are very sensitive to over temperature. I tried to use some 5 watt CFLs in some enclosed ceiling downlighters that previously had used 50 watt halogens, and failed to get more than 1 month out of them.

Be aware that some manufacturers may make their lamps more robust than others. Higher priced brand name producers might be more likely to use high temperature electrolytics and decent derating on the transistors than the lower prices copies that can be obtained.

Are you using the CFLs in enclosed fittings designed for filament lamps?

I would be a little surprised to learn that a free-flowing ambient of 40C was too much for decent life from a CFL, but would not be astonished.