I have a 32 inch inseam, and my knees sit next to the gas tank, so no heat felt. Are you wearing trousers or shorts? If you ride in stop and go traffic in hot weather, the radiator fan will blow some hot air back at you.
Wearing basic knee protectors either over or under pants legs will help with both heat and cold.
I have a 2009 FZ6R, I am 6’1 and when I am on her my knees are on the gastank. From 2009 to 2014 I was a year round rider here in NC (no car) and on the cold part of the years I would heat my hands on the engine. But other then that and what BluePill said in the summer (up to 110 degrees) I would get hot air blown on me from the radiator at stoplights. I have never burned myself