This is the latest outlook for the next four weeks from the Japanese Met Agency the JMA. It is not meant to be a forecast but a general outlook. I have added the 3 images together and rotated them and added a red line so you can see the UK. Blue colours are low pressure area’s and oranges high pressure area’s.
Week 1, 12th September to 18th.
High pressure will be firmly in control this will bring a fine, warm settled period of weather with the temperatures around 1-2 degrees higher than average for mid September, it should remain overall dry.
Week 2, 19th to 25th.
The UK looks to be in between high pressure to the West located over the Atlantic and Low pressure to the East over Europe. This period looks like the temperature would be what you would expect for this time of the month. It does look like there will be slightly above average rainfall.
Week 3-4, 26th September to 9th October.
This is a two week period so we will start to see a change taking place with low pressure sitting over the UK. The temperature will be around average or just below for the end of September early October. There will be above average rainfall.