It's not just about the winter where you are...it's the winter everywhere from origin to delivery. Face it, I'm in San Diego, it was 70 degrees the last shipment I got. I've never had crickets delivered by someone wearing long pants...but those crickets have been in cold during the trip.
What I liked about the Timberline pack was that they used the vented box. They put it inside a larger box.
I ordered my previous shipment from someone else and it arrived in "winter pack" which was completely sealed shut. Their customer service said they put in 25% more to offset the loss in transit.
So....I had a lot of dead crickets arrive with my live ones and somehow, that shipment was never good. They all died off quickly.