So the last major detail (full correction and coating) had to be done at night. I started at 5pm with the typical stuff, wheels/wash/clay and went right through to 1AM.
I started the next morning at 8am so I could get to the coating before temps exceeded 100. By the time I finished the vehicle, next day afternoon, it was close to 112.
So yeah, If you can deal with 3 or 4 months of excessive heat, late September/October through April is where the bread and butter weather is. But luckily it doesn't change too much. Products react much differently in extreme heat, polishes and compounds will dry out... Even GG FCC which is dustless will dust.
You just have to make provisions, adjustments and try to do stuff at night. But I'd rather deal with that than bitter, bone chilling cold. At least I don't have to clear 4' of snow.
Regarding winter routines, once it gets below freezing there really isn't many choices.. Your hose lines must be disconnected or they will freeze and possibly burst... And laughably turning on the water will freeze in the hose. One time trying to get a car done before temps dropped, I could see the liquids freezing on the vehicle. Your done.
Using High Lubricity products like Megs D114 (discontinue), McKee's N914, or Optimum NRW (ONR) are all great rinsless washes. What you can do is a touchless carwash to get bulk of the crap off. Those are good because they get the undercarriage. The only word of caution is if you have a light colored vehicle and have clear-bra. Some of the strong detergents and cleaners in the car-wash can stain PPF.
When you get home, fill a couple of buckets with water from say the bath-tub or utility sink and in one of them add your rinsless wash solution concentrate. I prefer chenille wash mits vs. microfiber. I start with the top down and do a typical two bucket method wash, except you wont be hosing the car off, as the products say "rinsless". Make sure your buckets have gritguards and you frequently change out mitts and rinse water before going to the bucket with the concentrate with the mitt.
You can do this all in your garage since you will be dropping water all over the floor, but not like a hose the concrete or epoxy floor should be fine. Then use your MF towels and apply your QD, or what have you.
I have some old posts about winter maintenance with pic's... I'll have to search or dig through those. I think in the pics snow is still on the ground...