This phrase means to understand what is happening in changing circumstances and to be able to anticipate the future. The weather or windward side is the side from which the wind blows. For sailors, huntsmen and farmers knowing where the windward was at any time was obviously important, that's why the phrase came to be synonymous with skill and understanding. The figurative sense meaning the tide of opinion, was in use by the early nineteenth century.

Übersetzung:

wissen, woher der Wind weht

Gegenteil(e)

The opposite of "know which way the wind blows" is "don't understand much".

Synonym(e):

You could also say: to understand what is happening.