Here are the scripts and data to make the wind rose:
Download either
sfo1998.dat.gz (116 kb)
and decompress it with gunzip sfo1998.dat.gz .
Or grab
sfo1998.dat (587 kb).
Column 5 in sfo1998.dat has the windspeed in knots, and
column 6 the wind direction (from where it is coming from) in degrees.
Download BinTheData.py,
which reads sfo1998.dat and outputs rosebin.dat .
Download roseplot.py which
reads rosebin.dat and produces windrose1.svg.