I never had problems with ammo by hunting under very low temperature . In hot climate area is the situation a little bit different . My allround cartridge in Africa is the 460 WM and shooting factory ammo is a problem by very high temperature . A reason for "tropical loads" , reduced loads , by reloading this cartridge or another express cartridges . To select a powder relating to the climate make imho no sense . Fast or low burning you can have pressure peak's .

The storage in Africa is not the problem but to carry the ammunition in the sun . The reason why i dont use open ammo belts . I take my cartridges in a pocket on my belt .