19/06/2026 – Heat AND humidity, causing impacts – Met Office weather forecast UK

0:00 – 3:05

The heat starts with a wobbling jet stream and one crucial Atlantic low

The story begins with a weather map that looks almost misleading. At first glance, low pressure near Iceland seems to be running the show across the UK, the kind of setup that often brings unsettled weather. But then the presenter points further west and spots the real plot twist: the jet stream is weakening and turning wavier. In the first half of June, the jet stream had been shifted south and had more "oomph", repeatedly firing low pressure systems at the UK. Now the pattern is flipping, and that contrast is what opens the door to heat. By Saturday and Sunday, high pressure builds north from central Europe. That means the rain-soaked parts of Scotland, Northern Ireland, and northern England begin drying out as weather fronts are shoved further north. The weekend improves in a very British way first, drier, brighter, increasingly warm, before turning more serious in the south where the hottest air is gathering under a broad zone of high pressure over the near continent. The most important actor, though, is a low coming out of North America and heading into the mid-Atlantic. The presenter stresses that most computer models agree on the broad picture, high pressure building, heat arriving, but the subtle differences in the track and depth of this low make an outsized difference. If the low is deeper, as in the Met Office model, it slows down more and forces a stronger ridge of high pressure ahead of it. That pushes higher temperatures farther into southern UK and lets the heat last longer. That is the curiosity at the heart of the forecast. Not whether it gets hot, because most models say it will, but exactly how hot, how widespread the heat becomes from Tuesday onward, and how long it hangs around. The forecast is not hinging on a simple "sunny equals hot" pattern. It is hinging on the shape and behavior of one Atlantic low, and that small upstream detail could decide whether southern Britain merely gets a very hot spell or flirts with record-breaking June temperatures.