As stated above, with the MHP, outdoors for even the first few days in very cold weather is a good option. I moved chicks just a few days old outside with an MHP outside the last three broods. Every chick thrived. And integration at 4 weeks was a breeze.Several of us brood in the coop straight out of the incubator or from the post office even if the outside temperature is below freezing. As long as you can keep a spot warm enough in the coldest temperatures and a spot cool enough in the warmest temperatures it works great. If you set up the Mama Heating Pad correctly it can work.
I assume you have read this thread.
Mama Heating Pad in the Brooder (Picture Heavy) - UPDATE | BackYard Chickens - Learn How to Raise Chickens
Good Luck.