HUGE swings in temp can have a big effect on ballistics.
When I lived in Maine I would typically reload all my ammo in the summertime. Our house did not have air conditioning and it would be 75degs inside.
The problem was . . . . my 223Rem ammo was shot on a 10 above to a 10 below night while coyote hunting in Jan and Feb.There would be a pretty significant drop in velocity until I learned how to load for it. ---- SAWMAN