I am currently doing a final project, which I have to create a map of 2012 average precipitation of lower 48 states by using natural neighbour interpolation. The problem is that how can I get the data? I already have the data of 2012 from NOAA website in .CSV format. There are more than 80000 geographical locations in the file (http://www1.ncdc.noaa.gov/pub/orders/cdo/434898.csv) Would it be possible for me to use them to create the map and if anyone has any idea for me about getting a data please help.
Display XY Data > Natural Neighbor Interpolation - use the points you just created as the Input Point Features and the Z value set to average precipitation.
That will get you a raster surface of rainfall which you can represent how you choose.
*Be aware that with Natural Neighbor Interpolation, you may need to add some 'Anchor Points' so as to ensure complete coverage of the US.