What does due South mean?

"We use the phrase "due north/south/east/west" to mean the direction that is directly or straight towards the north/south/east/west accordingly. So the sentence, without any ambiguity, means that the wind is blowing directly towards the north (south to north)." https://ell.stackexchange.com/questions/47825/what-does-it-mean-for-wind-to-blow-due-north

http://www.ldoceonline.com/dictionary/due-north-south-east-west

http://www.seatalk.info/

https://www.vocabulary.com/dictionary/due%20north