Without the check valve, you will be pumping the same water over and over again. That's a good way to run up your electricity bill and wear out pumps.
If it's freezing, then you will need to insulate.
If this is in a crawlspace, then it's very doubtful that it would ever freeze.
In the Seattle area, I pump my mothers yard when it rains. It has a check valve without the hole drilled in. We run 150 feet of pipe to the public storm drain with about 15 feet of head. This drains three properties. One time the neighbor replaced the pump and left off the check valve. The water in the hole was getting pretty warm from cycling over and over again through the pump impeller blades. Or maybe it was the motor warming the water from the constant use.