Your Not Carrying the Cooler?
In the past I develop loads in what ever weather it was and petty much do the same now. Being I was mostly in S. Cal it didn't make much differents. I had a load in IMR powder that was grouping under 1/2" @ 100yds. Temp was in the 40's to 50 range. Let it set until later on that year or end of June (80-90 dgrs). I fired round a shot using the same load figuring on shooting 5 rounds. It blew the primer out of the primer pocket. When home that day and took apart 49 rounds. Gave-a-way about 16 lbs of powder.
The other is once I develop a load for that rifle. It's what I stay with. First in grouping, then cold bore shots. If not on the money, I contenue working on the load until I achieve that. Weather be dam. All cold or hot weather does is increase or decrease the velocity of the bullet. Grouping should stay about the same That does change the hit location some. Again it goes back to what type of powders you are using.
What types of powders are you using? Did you open up the chart I sent out?