title: Extract monthly data from hourly resoluted netcdf file in nco
body: <p>As the title indicates, I want to extract a time period e.g january for a variable, <code>wind_speed</code>, from a <code>.nc</code> file that consists of wind speeds with 3-hourly resolution during one year. I would like to do this in nco if possible.</p>
  
  <p>I tried the following method: <code>ncrcat -O -F -d time,1,248 -v wind_speed sfcWind.nc out.nc</code> and it works. For this method I need to calculate the time span during the chosen month. Is there any other method in nco where one can specify the month and get the corresponding data?</p>
  
  <p>Another thing is that if one wants data for dec, jan, feb then this method cannot be used, or at least to my knowledge. Any suggestions here?</p>
  
  <p>Best Smail </p>