A shift in the wind direction across Sydney is behind the city's record wet year

There is a secret ingredient behind Sydney's record wet year, and it's not La Niña or climate change.

And for those who know weather, it's not the negative Indian Ocean Dipole (IOD) or the Southern Annular Mode (SAM).

So, if it's not the usual suspects, let's find out the real reason Sydney has suffered through more than 170 days of rain.