This is the outlook for the next four weeks using the Japanese Met Agency model. I have added the 3 images together and added a red line so you can see the UK. Blue colours are low pressure area’s and Oranges high pressures.
Week 1 14th to 20th September.
A low pressure trough is over the UK with high pressures to the North of Scotland. The JMA see’s this been an unsettled and cool period, with above average rainfall and below average temperatures.
Week 2, 21st September to 27th.
The JMA see’s a big change with a large area of high pressure stretching across the North Pole down to the UK and over to Northern Europe. This should start to become settled, drier and temperatures around average for the end of September.
Week 3-4 28th September to 11th October.
The JMA now see’s a change back to low pressure. This is a two week period so you would say there would a change at some point around of end of the month. It looks like early October will be cool and unsettled with above average rainfall.