IPA: /əˈwɛðər/
KK: /əˈwɛðər/
In the direction from which the wind is blowing, or towards the side where the wind is coming from.
The sailors adjusted the sails to catch the wind aweather.
The word 'aweather' originates from Old English 'onweðer', meaning 'against the weather' or 'in the face of the weather'.
Think of being 'against' the weather — that's what 'aweather' means.