I have noticed large groups of Fieldfares around in the last week. I believe
these often move South in search of berries when the weather is extremely
cold or snowy in Scandanavia and Northern Europe.
The last time I saw these and Redwings in large flocks was 1963.
Now I think it is a rural myth to say they are a harbinger of severe weather
in the UK but ......... (also see Will's forecast, which is sensibly
uncertain about potential outcomes).

Dave, S.Essex.