Too cold for monarch?

I'm hoping you can help. I live in Ontario, Canada. We found a caterpillar on September 17th and brought him in with milkweed... he was born just yesterday. We are expecting highs of 6 degrees Celsius and lows at 0. It has also been windy. We tried to release him yesterday and he just clung onto the sedum for dear life for hours, so we brought him in. We are trying again today, but he's still just sitting there. I was told by someone at the local butterfly conservatory that he would be fine, he knows what to do. But I think it's too cold for him to move, and I don't foresee it being warm enough and it's almost November! Is it more humane to bring him in and keep him in a safe indoor environment or to leave him be and hope that he flies away? What to do?
Thanks.

Karen says:
It is difficult to keep a butterfly alive for a long time inside. I would recommend that you bring the monarch outside. Check the weather forecast and if warmer weather is predicted in a few days, you could wait until then (or at least a sunny day :) There is a good possibility this butterfly might not make it to Mexico, but at least give it a "fighting chance".
P.S. In cold weather, the monarch stays still and goes into a type of temporary "hibernation" until the weather turns warm enough to fly.