I am very good friends with the Hodgdon family and I have a couple of friends that work at Hodgdon powder company. I have asked the same question about temp sensitive powders. Their answer in short is, any Hodgdon "extreme" powder or any IMR "enduron" powder is temp stable. Other powders that are not in the Extreme or Enduron lines will be effected more by temperature swings. Also, all temp stable powder is an extruded powder. However, not all extruded powder is temp stable. I can't speak for other powders out there since I only use Hodgdon and IMR. Hope this helps a little.