Same here, it's exhausting. We have tried prompting a lot, trying to let him choose clothes, I also use a treat now and then and sometimes open the door and say 'is it cold out do you think we should wear a jacket?'. I sometimes just bring the jacket with me and out it on outside when he is distracted. Can try a chart at the door so they get a check or sticker when they out their jacket, boots etc on. Good luck!
I use bribery. If you put on your mitts we can play in the snow for a few minutes, you can have a cookie in the car, etc. Sometimes it works. 🤷