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, 3rd to 9th May.
Low pressure is over most of the UK bringing a cool northerly airflow. We see temperatures 2 or 3 degrees below what we would expect for early May. Rainfall will be around average with some showers but overall fairly dry.
Week 2, 10th to 16th May.
High pressure will be in control stretching from Scandinavia over the UK and down to Spain and Portugal. We can expect to see some very pleasant warm conditions with the temperatures around 2 degrees above average and its looking like it will be mainly dry. The exception will be Scotland where it will be fairly wet.
Week 3-4 17th to 30th May.
This is a two week period and we may see a gradual change. The JMA thinks there will be a small high pressure area around the Bay of Biscay. This would bring South-westerly airflow this would bring above average rainfall. Temperatures will be around what you would expect for the second half of May.