Must be a lot warmer at your end of the country than mine ? Took the Interceptor in for it's annual service today & it was just nicely comfortable in normal textile riding gear, linings in & just a short sleeved base layer underneath. I was hoping to take a Bullet demonstrator out for the day, but it was already booked out so just came home on a 14 year old CBF500 Honda loan bike. When I went back to collect the Interceptor, the "test rider" hadn't turned up or bothered to call & cancel - b&stard ! Mrs B's car said it was 24 degrees, so far from "too hot to ride" up here.
For places where it does get to be "too hot to ride" we have ventilated suits. Mine is a Hein Gericke Air suit jacket with IXS trousers after the Hein Gericke originals inexplicably shrunk (ahem !) and Alpine Stars moto cross gloves. Mrs B has an IXS suit & Dainese unlined leather gloves. Both suits need the temperature to be about what it was today as a minimum & stay comfortable into the mid-30s.
Last summer, while staying on Lake Iseo, it stayed over 42 degrees C with high humidity & that was too hot to ride ! It was 38 degrees at the top of one of the passes (name escapes me at the moment) at around 2000 metres. Only rode once in the three days we were there & moved off early to get some altitude near Vipiteno. Still very hot by UK standards (38 degrees), but a lot less humid.
Mid-30s temperatures are not unusual in Central Europe in late June / early July when we tend to go, so the ventilated suits have been a good investment. Far better than having to peel a set of sweat-soaked leathers off at the end of a long day !
In s such hot conditions we carry plenty water & stop to drink regularly to stay hydrated.
I must have a greater imagination than some to be able to visualise the damage that even a medium speed rider-road interface could wreak on my bod than those who choose to ride in shorts & tee-shirt.