Hi Jake; As with most room temperature cure epoxies (even West System, T-88, Aeropoxy, as well as others), the service temperature is somewhat lower than the value used for elevated cure systems or resins like Vinylester. Generally you can figure that an average service temperature value for room temperature cure epoxies is between 160 deg. F to about 185 deg. F. At that temperature the strength is still about 80% or so of the room temperature rating. But there are two things to keep in mind. First, in a joint, the epoxy is not likely to see that temperture, even in a Scottsdale sun, since the wood (or fiberglass) around it is actually a good insulator and thus it would take a lot of heat soaking to affect the bond significantly. Also, the wood surrounding the bond is significantly weaker than the shear strength the epoxy is capable of. The shear strength of the epoxy is probably on the order of 3,500 psi., give or take a bit. The shear strength of the wood parallel to the grain is only several hundred pounds per square inch so, even if the temperature did affect the epoxy, the surrounding wood is still weaker.