Modern materials are not effected by temperature the way they were back in the days Bowhunter45 and I started bowhunting. But, it does have some effect. Some bows more than others.
A couple things to consider...
Clean and replace grease in the pivot pocket. Only need an extremely small amount of grease. And if a shop does it ask to see what grease they are using. Make sure it is a good lithium grease. That stuff rarely gets stiff in cold weather. I've experienced some real bad results with silicone greases.
Heat from the car can get rather high. So try to keep your bow clear of heater vents. Doesn't effect limbs like it used to, but it can really play heck with your strings. Especially when your strings are wet!! Single cam bows seem to be the worst offenders with this. As are the single material strings like 8125. Still dang hard to beat 452X or XCel for all weather consistency. Might not be as pretty as the bright 8125 or 8190 materials, but nobody looks at your bow strings when you post a trophy animal picture.
Rest silence material!! I see guys all the time with huge amounts of fleece on their arrow rests. In nice dry weather the arrow settles in nicely and you get a good silent draw. But get that stuff full of water and things change. Freeze that water and you aren't going to get consistent arrow flight no matter what you do!!! Very thin moleskin
(shave it if you have to), cloth BandAide, fingernail polish or 3M waterproof white labels
(a personal favorite) will keep things quiet while giving little if any change in wet and/or freezing weather.
Mark your peep sight location. As string material shrinks, things get cold and stiff, and as you hit the brush hard peep sights do get bumped. I use two different methods to double check my peep location regularly. First I use a Sharpie to mark the location of the peep on the bow string itself. Some string materials require you to reapply often to make sure it stays visible. Next I measure the distance from the arrow nock to the center of the peep aperture. I then write that distance somewhere on the bow using the Sharpie. With a little alcohol you can usually remove that mark if you need to change distance later on.
It should go without saying that you also want to mark the D-Loop to arrow rest "Up" position as well. Any cheap bow square will allow you to do this. Finally, as mentioned above...shoot with an arm guard and/or your heavy cold weather clothing before you get in the field. String contact with the collar, sleeve, armguard, zipper...all have an effect on POI. No bow, now release, no fantastic shooting theory will overcome string impact. Doesn't take much!!! Even if you have no string contact the heavy clothes can effect your anchor point / head position too. And don't just stand at the shooting line and shoot like a California high wrister
Get on your knees, sit on your buttox
(maybe even in a chair), and shoot back over a shoulder, up, down any way you can think that you may end up needing to shoot in the field. Hunters rule...your shot opportunity will most likely come where you least expect it.
