Coldest mid October of the past 30 years in north-west Germany:
Today and tomorrow the afternoon temperatures will stay below 5C / 41F! With a dry northeastern continental wind it feels like a nasty day in January. This has occasionally happened in late October, but I can't remember such a cold spell/spill in the first half of October.
Considering September and October together in my region, I haven't ever seen such an absense of summer just from September 1st onwards. The monthly maximum in September was just 22C (72F), while on average it would be around 26 (79F). Often October has delivered several warm days when September was disappointing, but again nothing, maximum in October was 20.5 (69F).