I use a leather apron, and have for years. I do a lot of forging, welding, grinding, and soldering, and am not fast enough anymore to get out of an apron that is on fire. Finishes, with linseed oil as an ingredient, are susceptible to spontaneous combustion, but not when on a leather apron. And as for hot, where I live summer temperatures of 110 are not unheard of.
Hungry Horse