Dean
Firstly, what type of precip data, hourly, daily, monthly, annual, mean annual, etc.?
Secondly, higher elevation does not always mean more rain, there are rain shadows, for example. So you may need additional info. In studies that I did many years ago I found that distance from the sea and surface roughness also played an important role. Also the rain-bearing direction.
An extensive literature search will help 🙂
Regards
Steve