There are no charms in cycling so great that sane folks should endure physiologically hazardous conditions. Emergencies are one thing, but temperatures and humidity hurtling toward three digits are prime indicators to Chill-The-Heck-OUT. Apart from exercising type-A behavior [bless us, preserve us, and mostly spare us], I can't think of any training benefit. . .at least until Olympic Swooning in Sweat is recognized as legitimate. These are good times to maintain bikes and mess around with mods.

Gear [above] has it right; cycle during the crepuscular hours. . .like coyotes. There's a reason critters aren't out in the heat of the day.

I s'pose if you must ride the heat stay hydrated and nourished. . .and we'll send the rescue folks 'round.