What causes cold temperatures to move earlier than they usually move? Here in Buffalo the weather was 9 °C. However, everyone had winter coats and hats on. There was no snow, but it was very very cold. I have a feeling that the Great Lakes may have something to do with it.
The Great Lakes contribute to a huge thermal inertia, which will even out short-term temperature fluctuations, and delay the smoothed seasonal temperature peak. On the other hand, more sinuous looping of the jet stream is likely to have a comparable, if not larger, effect upon the temperatures in Buffalo. The process is this: As global warming progresses there is a disproportionate warming towards the polar regions. This results in a reduced temperature gradient with respect to latitude. It is this gradient which is largely responsible for the jet stream intensity. As the jet stream weakens it becomes more sluggish and sinuous, resulting in regional hot and cold anomalies. If Buffalo happens to get caught in one of these jet stream loops, it is quite possible to have periods of anomalously low temperature, even though there is an overall North American warming. It is also possible for Buffalo to get caught in a negative loop, and hence experience anomalously hot temperatures.
I'm guessing you're talking about the cold-snap centered around October 2 and 3. We got it here too in NYC. It was surprisingly cold for 2 days for this time of year and it came on rather suddenly.
I don't remember, and haven't been able to find a weather report from 4 days ago, so the precise reason for that cold snap escapes me, but it hit a significant part of the North-East US and perhaps a bit more than that.
Generally when wind blows in from the North, we get cold air, so that's probably about what happened. The great lakes probably kept Buffalo slightly warmer during that period, not colder cause the late water was probably warmer than the air temperature.
This article is somewhat related, though I'm not sure how well it applies to the dates I think you're talking about.