How long do Weasels stay white?

I'm in southeastern MN and looking to set some weasel traps within the next week to try for my first one. I don't want to catch a weasel that is in its turning phase and was wondering if anyone knows how long until they typically start changing back to their brown summer coat. Does the amount of snow on the ground affect this, or is it purely on the change in daylight present each day?

I don't know the answer to your question. But some of the coolest looking ermine pelts that I've ever seen are when they are changing color. It isn't an instant process but rather takes place over a period of time. When the white starts to become brown (or vice versa) the mixed colors can be really pretty. Just saying.

The change to summer pelage will not occur for some time BUT in your area they are already well past pure white. Most begin to yellow by mid-January and continue to get nastier as spring progresses. Figure to begin trapping for them Thanksgiving week or the week after and trap for no longer than 6 weeks.

Good luck on the weasels! I just made up a couple boxes, and have had them out for a couple weeks. Not a single weasel. Only deer mice, a vole, and possibly a coon. I dont think weasels exist here

A couple of year back in the auction thing heated up when the II and the III were offered and these went higher than prime pets.( there must to been a demand for a movie that was in the works)

The yellow is from spray and urine and not molt.
The backside of the pelage gets a off-white or yellow hue when they start to molt.

2 degrees of latitude is a weeks change in molt......elevation is another factor

Thanks for all of the responses guys, some very interesting info. Is there anything that can be done to fix the yellowing of the fur after you have caught one?