My mom refuses to take me to get my hair cut?

I haven't had my hair cut since September. My mom comments about my hair but she won't take me to get it cut. It is almost 2 feet long. I am going to the beach a lot this summer. In less than a month I will be near the equator so the sun will be scorching hot. I have told her multiple times that I need a hair cut but she doesn't see why. Even in just 90 degree weather I am burning up because of my hair. How can I convince her to take me to get it cut? I am 13 so I can't take myself.