Firstly, I’d like to apologise for the lateness of this forecast, I’ve had limited computer access due to my laptop charger breaking, but a new one has arrived and I’m back.
If you were hoping for an Indian Summer, I’m afraid it looks like you’re going to be disappointed. Although September did start off on a fairly warm, settled note, it didn’t last long and Low Pressure has now taken charge of the United Kingdom bringing rain and strong winds to some areas and this pattern looks like it’s going to continue.
The reason being is that we’ve finally lost the High Pressure systems that have been sitting across the Arctic and in the Atlantic for the majority of summer meaning both the North Atlantic Oscillation and the Arctic Oscillation are now in a weak positive
They’re forecasted to stay that way for the time being too which rules out any warmth at least until the middle half of the month. If we also take into account the CFS pressure anomaly charts, which have proven to be quite accurate recently and use these in conjunction with the Sea Surface Temperature Anomalies
The first chart above shows the CFS Pressure Anomalies and tells us that Low Pressure is likely to be dominating the UK weather, with a mean trough situated over the United Kingdom bringing spells of rain and strong winds to just about all of us through the month. The second picture above shows Sea Surface Temperature Anomalies, and whilst slightly below average to the South-West of the UK, we do have above average Sea Surface Temperatures around the United Kingdom, which is helping to aid these low pressure systems.
Taking the above into account, September as a whole is likely to lack any prolonged warmth, with temperatures generally around, or slightly below the Long Term average, rainfall is likely to be average or slightly above average due to low pressure systems bringing spells of rain across much of the United Kingdom, those in the North and West likely to see the worst of the rainfall and strong winds. Although there will be days where we’ll see some warmer, brighter weather, they will generally be short lived with unsettled weather waiting in the wings.
Towards the end of the month, I think we’ll see the low pressure systems across the UK gradually begin to fill in, turning things a little more settled, though temperatures are unlikely to respond too much, I expect we’ll see a weak ridge of High Pressure returning in the Mid-Atlantic too, as we move towards the end of the month.