The builtin output formats for wgrib are binary: single precision CPU native format ieee: single precision big-endian IEEE (32 bits) grib: text: Someone had the need to produce double precision output. One may question their wisdom because probably all GRIB data have less precision than the single precision floating point format. Nevertheless it was easy to modify wgrib to output double precision floating point numbers as the standard binary format. (Writing dp ieee is much more difficult.) Kludge number 102: Edit the file wgrib.c by changing all occurances of float to double. Change the line #include back to #include Remember that you must change ALL occurances of "float" and that word may occur more than once on a line. Compile normally and if all goes well, the "-bin" option will now produce double precision floating output. Don't forget the default format is "-bin". Note: The kludge looks good but hasn't been examined with a fine-tooth comb. I should probably change "float" to FLOAT and use a typedef. However, this change is really low priority. END OF KLUDGE NUMBER 102