Unfortunately, it’s often difficult to find a car insurance policy that will cover your car for the summer only. Typically, car insurance will be sold for terms of six months or one year at a time rather than on a month-to-month basis. However, you might be able to get a reduced rate for the months that you’re not driving your car.
If you’re absolutely certain that you won’t be driving your car after summer is over, you can also cancel your policy once you go back to school. This will drop all coverage for your car, though, so your car won’t be legally driveable until you get a new policy.