It is worth noting that many newer hard drives (and esp many SCSI discs) run much hotter than older discs. Even a 5400 speed drive in my RPC gets up to 40+ degrees and that's in a dedicated cooling bay (Coolermaster cool-drive). Thus druck's point is extremely pertainent - it is VERY common for hot weather to result in aging RPCs to struggle/crash etc. I used to experience it most summers from about 2000 onwards til I replaced the most troublesome machines with RISCubes.
As such, if druck's warning helps *one* person avoid catastrophe/data loss, it has been a worthwhile and significant excersise.