So my lab retrieves, is not gun shy, is extremely obedient, but cannot stand those days when it is 25 degrees and the lake is cold. I bought him a vest, and it seemed to help a little, but he just refused to retrieve when its cold. He will get in to about chest depth but wont go further. If it's about 50 outside, he does great but with the colder weather I don't know what the problem is. I've hunted with other labs that do it without any equipment and have no problem, so I'm not quite sure what to do at this point. Any suggestions?

A good trainer can fix it. Force to water will most likely be their tool.

He can do it, he doesn't want to. Have you force fetched him and tried the "fetch" command? Not saying that will work but it could?

Another trick you can try is have a buddy bring his dog...that sometimes will fix that issue too. The dog gets amped up enough that there is competition for his birds he will pay not attention to the cold water.

Good luck.

The same dog you had this trouble with last year? Should have done your water force during the summer when it was warmer. As Judd said get him out on a play day on a very cold day with some other dogs that love the water and get him socialized to the cold water. Then do some repetitive training when it is cold in the same weather and situations you hunt.

What they said ^^^^. I would recommend not reinforcing bad habits. If the dog has not been force fetched work on that at home but don't continue taking the dog. If your dog has been force fetched but not water forced then start wading out with the "here" command and when you get to the bird command "fetch". Enforce the standard. If you have not force fetched do not attempt this and understand that you are going to be limited to water you can wade. You must also enforce EVERY time. That means taking the dog out to all birds until they finally go when sent.

Your other option is to forgo the season and water force next spring.

Good luck.

Dogs are competitive, that's for sure. They get jealous. Especially if the other dogs are getting all the praise.
Use that.

He'll come around.