Hi
my14 mo old has ALWAYS resisted dressing in any incarnation. Sometimes I just wrap him up in a blanket on the way to the car and leave it at that. (he has some clothes on just not all I would like for the weather)
Lower your expectations, think of alternatives (my baby will tolerate a heavy sweatshirt better then a real coat) and be flexible. I think I often overdressed my first child and am trying to be more sensitive to actual temperature with my second!

Above all, think....What is the worse that could happen if he didn't have his coat on between now and the car? After that I bet you go right into a store and delayer again. He is unlikely to be playing in the snow as of yet!

For the child who wonders away as you dress him....I do it in stages....
First the diaper or onesie
Then the next part after he does this or that.
Sometimes I throw the next part over to his father on the other side of the room to 'catch' him for the next piece of clothing...
Etc