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, 21st to 27th August.
High pressure is firmly in control to bring some summer like weather. With a south-easterly airflow we will see temperatures 2 or 3 degrees above average with dry conditions.
Week 2, 28th August to 3rd September.
A low pressure trough will be over the UK with high pressure to the East and West of the UK. This will bring a change in our weather from the previous period. Rainfall looks like it will be above average and the temperature looks to be around average for early September, except for Cornwall where the temperature could be slightly below average.
Week 3-4, 4th September to 17th.
Another change will start to take place with high pressure over Scandinavia and slack pressures over the Atlantic and the UK. I would think we would see overall a westerly airflow bringing showery conditions with temperature around average for mid September.