I have brown hair with lots of highlights that have only gotten lighter through the summer.?

So now I'm basically blonde. The problem is that my roots have grown out and I can't get a hair appointment any time soon. I'm feeling brave and thought I would color it myself. I was thinking of using a temporary color to cover the roots but I don't know whether to use a dark blonde or light brown. My eyebrows are also pretty light and I want this to look as natural as possible. Please help i don't want to end up looking like a freak!!!!I have brown hair with lots of highlights that have only gotten lighter through the summer.?
If you're only going to cover the roots, you need a color that's blond to match the rest of your hair. If you are going to go with the dark blond or the light brown, then color all your hair that color. It will still be slightly darker at the roots, but at least the change will be subtle.