In winte, there is snow in Kusatsu Onsen.
If you came here by car, you have to prepear the non-skid tire for your car.
Please make sure your car wear non-skid tires, when you rent a car. If your car don't wear non-skid tires, you should get the staff to change the car.
If you can not prepare a car with non-skid tires, I recommend you to come to Kusatsu Onsen by train or bus.