How do I lighten my dark brown hair naturally?

Okay so my hair is dark brown and I want to dye my bangs temporarily blue with kool-aid or food coloring or something temporary. My parents won't let me dye it permanently or bleach my hair. I need to get my lighter though, if the blue coloring is going to show at all. So I need to find a way to lighten it naturally and fast!

Everywhere I look, I see lemon juice and sunlight. Lemon juice is a good idea but it's still the dead of winter here in the Pocono Mts so sunlight is kind of out of the question until April. Yeah, long winters.

Anything else? My hair is pretty dark but its not black; the sun gives me light brown highlights sometimes in the summer. However, I can't wait for the sun to come out.............

Ideas?How do I lighten my dark brown hair naturally?
oh you can put pure lemon juice on it and then just go out in the sun and after a few days you will see that it will turn lighter (works best in summer)How do I lighten my dark brown hair naturally?
henna mabey? you can get them at local indian grocery stores