Code to parse METARs with Tom Pollard's library

gistfile1.py

def extractWind(s):
    """Parse a metar and return wind speed, direction.
    If gusts, reports peak speed. Variable wind direction reports prevailing."""
    
    # clean the input
    if s.endswith("="):
        s = s[:-1]
    if s.endswith(" LAST"):
        s = s[:-5]
                  
    metar = Metar.Metar(s, month=12)   # fake out month
    
    # Take peak speed in case of gust
    if metar.wind_gust:
        speed = int(round(metar.wind_gust.value("KT")))
    else:
        if metar.wind_speed is None:
            raise Exception("Wind speed was None: %s" % s)
        speed = int(round(metar.wind_speed.value("KT")))
    
    # Extract the wind direction: not sure what happens in winds varying 60deg
    if metar.wind_dir is not None:
        direction = int(metar.wind_dir.value())
    else:
        direction = None
        
    # Treat 00000KT as no direction
    if direction == 0 and speed == 0:
        direction = None
        
    if direction is not None:
        if direction == 0:
            raise Exception("Wind direction was 0: %s" % s)
        if direction % 10 != 0:
            raise Exception("Wind direction not a multiple of 10: %s" % s)
    return (speed, direction)