Doing the numbers for an assignment @ sea level 30-34C every day, high humidity, over salt water. I'm quite unfamiliar with the 76 series, what kind of performance/payload would a 76A model be capable of under these conditions?
Give HeliJet a call in Vancouver, I'm sure they'd know. They operate S76-A in both corporate and ambulance configurations, and Vancouver can get stinking hot and humid. Think they were close to 40C a few weeks this last summer.