Most JHP that I've tested will spread just a little even when "plugged" producing a squared profile at the nose. Even this failed expansion is better than the slick profile of FMJ. I use 124gr. GoldDot in my normal carry gun and have never had it fail.
I had this issue come up in a 3 day LE class I was teaching. I went to a local thrift shop and picked up 4 hoodies, a denim and a leather jacket. I also picked up a large round of beef. On the range I layered the clothes on a single hanger, topping off first with the leather jacket. I placed the round of beef inside the layered clothing.
Using standard duty ammo from one LEO (Speer Gold Dot 124gr 9mm Luger), I had the LEO fire one round at the target at a range of approx. 21 feet. The round penetrated all layers of clothing without a problem and expanded nicely in the round of beef.
I repeated the process, this time swapping the leather jacket with the denim one. I had another LEO fire one round at the target, again standard duty ammo (This time Winchester Ranger T 180gr .40 S&W). The bullet had similar results as with the first test.
I don't see a need to change ammo with the seasons. Find a load that works for you and works well in your firearm, and practice often.
Any thought or information on the all copper bullets for self defense, like the Barnes hunting rounds? I kind of have tunnel vision with the Critical Defense and Black Talons so I haven't looked at much else, much to my shame.