Geese Flying North before Flying South?

Hello, It's the time of year when geese (and possibly other birds?) fly south for the winter, is it not? Well, in the past few days, I have seen many flocks doing exactly this. I know which way is south, because our back garden has the sun shining on it all day in the summer. However, in the days leading up to this migration, I also saw many flocks flying in a roughly northerly direction. Is this some horrible, weird anomaly caused by global warming, or can anyone on here please explain this behaviour? Many thanks in advance! Allan Morris