NMEA MWD datagram format
The NMEA MWD datagram provides the direction from which the wind blows across the earth's surface. The wind direction is related to north. The datagram also offers the wind speed.
Format
$--MWD,x.x,T,y.y,M,z.z,N,s.s,M*hh<CR><LF>
Description
1 $—:  Talker identifier
2 MWDDatagram identifier
3 x.x,TWind direction (True) (0 to 359 degrees)
4 y.y,MWind direction (Magnetic) (0 to 359 degrees)
5 z.z,NWind speed (knots)
6 s.s,MWind speed (metres/second)
7 *hhChecksum