Excellent points.
One of my main seasonal considerations (or determinents) is the heat of the vehicle interior year 'round but especially in the summer.
The temperature inside a closed vehicle in the summer sun can easily hit 120 to 160 degrees dependent upon your locale.
So the summer sun and the heat build up on BOB's and other gear in a closed vehicle preclude packing some items I would like to have that I might be able to pack in the winter.
Not only can the intense heat ruin some items in short order it can also reduce the usable life of other items.
Items to think about include butane fuel canisters and lighters, wax candles, some types of energy bars and other foods, etc.
For what it’s worth the coolest part of the car seems to be under the seats.
For things that you have to keep in the car like a flashlight and batteries, and some electronics, try using a soft-sided lunch cooler for storing them under the seat, keep your alkaline batteries separate from the electronics and flashlight, the batteries leak.
If the car is too hot to store lighters, it may be worth get a flint striker. I’ve tried several types, and the easiest ones to use are sold in the “welding supplies” section, and look like barbecue tongs stuck to a bowl. The ones sold in the camping section tend to take practice before most people can get a spark reliably. The welding flint strikers, all you do is squeeze the handles.
“Not only can the intense heat ruin some items in short order it can also reduce the usable life of other items.”
That’s something I haven’t even considered. And I’m sure a lot of items are probably useless right now.
This is such an awesome thread and group, you guys know so much!