This is the outlook from the JMA the Japanese Met Agency. It’s not meant to be a forecast but a an outlook. I have added the 3 images together rotated them and added a red line so you can see the UK. Orange colours are high pressure area’s and Blues are low pressure areas.
Week 1. 3rd May to 9th.
High pressure is over the UK and over the Arctic and over the North Atlantic. This will bring mainly a dry settled period, but temperature slightly below where you would expect them to be for early May.
Week 2. 10th May to 16th.
Low pressure stretches from the Atlantic over the UK and into Europe. This will bring a unsettled wet period of weather, feeling cool. Temperatures are one or two degrees lower than average with above average rainfall.
Week 3-4 17th May to 30th.
Low pressure is over the UK bringing again an unsettled period with above average rainfall and temperatures slightly below average for the end of May.