October is looking to bring a change in weather patterns across the United Kingdom. Medium range weather models are predicting High Pressure to build over the United Kingdom/Slightly to the East of the UK towards the end of September, so there are increasing signals that October will start on a dry, and fairly warm note, so those hoping for some sort of Indian summer, could be in with some luck.
Lets take a look at the NAO/AO
The NAO as we move into October is forecasted to be neutral/Weakly Negative, this would suggest a generally quiet Atlantic with High Pressure over the United Kingdom. The AO is forecasted to be neutral/Weakly Positive, this would suggest a weak Low Pressure will be across the Arctic,which is likely to lock in that colder air across the poles.
The chart above shows us the Global Sea Surface Temperature Anomalies, if we take a look at the Atlantic we have cold water anomalies to the South-West of the UK, this would suggest High Pressure will build in the Atlantic, keeping things relatively settled as we move into October.
Taking the above into consideration. October is likely to begin on a dry and quite mild note with temperatures perhaps peaking at around 20-24c, though this warmth is expected to be short lived. As we move into the second week of October High Pressure will begin to build to the North-West of the United Kingdom, this will send Low Pressure systems Southwards into Europe allowing an East/North-East wind to develop across the United Kingdom, this will bring in a fair amount of cloud and drizzle across many areas, feeling quite cool along Eastern areas with temperatures likely to be below average everywhere.
With Low Pressure over the Arctic, a complete Atlantic block is unlikely to develop, this may allow occasional areas of Low Pressure to skirt Southern England bringing more organized spells of rain. As the near continent continues to cool through the month, we will see slightly cooler air moving in across the UK which may allow some drizzly showers to turn to sleet and snow, particularly over higher ground.
Temperatures: Below Average
Rainfall: Below Average