That's an unknown. The rule of thumb for chemicals is every 10 degree rise in temperature halves the chemical life.
I've shot 1930's German 8mm ammo, some great stuff. I've shot 1980's 7.62x54r Bulgarian, it was erratic and nasty. My guess is that storage conditions made a big difference.
My approach is, that if the ammo or powder is stored at a temp/humidity comfortable for me, it's going to last.