The +40 Humidex days are... shite. That's patio + cold beer weather. My wife likes to swim in either Lake Erie or Lake Ontario on those days to cool down.yes humidity is a big factor. I traveled in Columbia in 2005, we had everyday 40+ C with above 90% humidity. I couldn't do anything. I was just sweating doing nothing. Last summer, I traveled to Iran and we also had 40-45 C everyday, but with very dry air. That was really easily tolerable.
But that's the first time in my life that I hear they ground flight because of excessive heat.
When I went to Wegas, I got off the plane wearing a jacket/jeans (It was April -- dress appropriately!). The people thought I was crazy. It was only 24*. But yeah the dry sucks for any period of time. We got nose bleeds from the air.
@dskeard : How long have you been in NFLD? That's a dramatic difference (Phoenix -> NFLD)!