The June flip: from record May heat to Atlantic westerlies in a single week

A week is a long time in British weather. At the end of May the UK was sitting under a blocking high, logging temperatures above 30°C for several consecutive days and — for the first time in any May on record — a reading above 35°C. By the first week of June, daytime temperatures in many areas were running more than 9°C lower than the same time the week before, with some locations seeing differences exceeding 15°C.

What actually changed

The Met Office's deep dive published on 3 June points at the North Atlantic Oscillation: it flipped from a negative to a positive phase. A positive NAO strengthens the jet stream and steers Atlantic low-pressure systems straight at us — exactly the pattern the May block had been holding at bay.

The early-June result: bands of showers and thunderstorms, the heaviest cells capable of 20–30 mm of rain in just a few hours, and gusts of 40–50 mph around the stronger convection. The most organised activity favoured northern and central Britain, with the southern chase domain catching the intermittent dry slots.

What it means for the chase domain

For southern-UK chasers this is the classic trade-off regime:

• Shear is back. A strengthened jet overhead means 0–6 km bulk shear numbers the May heat ridge never offered. Check the wind atlas — the deep-shear tiles have been live with it all week.
• Instability is rationed. Cooler, showery airmasses build CAPE in the low hundreds at best, usually peaking in narrow windows behind clearing rain bands.
• Setups are fast and scrappy. Line segments, squally gust fronts and brief spin-ups rather than sculpted multicell clusters. Timing beats positioning.

The longer view

The Met Office expects the unsettled, mobile pattern to hold through the coming days, with hints of pressure rising — and temperatures recovering to above average — towards the end of June. If that verifies, the next act of the 2026 season may look very different again. The 5-day outlook will catch the turn first.