I actually feel like making sure I stay hydrated in the winter helps against nosebleeds. I don't get them enough, though, to know if OP will help.
I know drinking enough water is important, though. The heat can really dry out your sinuses. One summer I went out to Wyoming to do some climbing. I came back East to return to school and had to get a check-up. Upon looking at my nose the doctor said it looked like i had been doing a lot of cocaine, it was so dried out! I think it was all because of the dry air out West and also that we were spending a lot of time up real high. I had been getting nosebleeds and actually jsut having a lot of pain in my nose.
The next summer I drank lots more water, used a saline spray, and received no comments like that again.