We are going to try and pour a basement in the next two weeks and tempertures are going to be in the low 30s day and low 20s at night. Is that going to be a problem or should I wait until spring which would really mess up the schedule

Make sure there is no frost in the ground where you are pouring.
If you do pour, do it first thing in the morning so you can cover and insulate the concrete by the evening. Concrete generates heat while it cures so if you can cover it with a couple layers of insulating tarp you should be OK. You can also check with your local pre-mix supplier about low temp concrete or additives such as calcium chloride.