32°C, then the breakdown: this week's heatwave is loaded to end in storms

Three weeks after the NAO flip dragged Atlantic westerlies back over Britain, the ridge is rebuilding — and the south is going to bake before it breaks. The Met Office has heatwave conditions in the forecast for this weekend, with 32°C expected in the south of England on Sunday and the chance of something higher on Monday. The UK Health Security Agency and Met Office have a Yellow Heat-Health Alert running from 15:00 Wednesday 17 June to 20:00 Monday 22 June across the East Midlands, East of England, London and the South East.

For chasers, the heat isn't the story. The breakdown is.

Why this setup matters

Every degree the south gains this weekend is energy banked for convection. Humid, high-dewpoint air pooling under the ridge is exactly the fuel a passing trough needs. The Met Office is already flagging an increasing chance of thunderstorms, particularly across the South East later each day, with the heaviest cells capable of:

• Flash flooding from slow-moving, high-rain-rate storms on baked, run-off-prone ground
• Large hail where updrafts tap the steepest lapse rates
• Frequent lightning and gusty outflow
• Travel disruption as cells track over the London / South East corridor

The chase read

This is a classic loaded-airmass breakdown rather than a sculpted shear day:

• Instability is the headline. CAPE climbs with every hot, humid afternoon — check the outlook for where the cap is weakest.
• Shear is the question mark. The ridge keeps flow light until the trough arrives; watch the wind atlas for the moment deeper shear noses in from the west — that's when scrappy pulse storms start to organise.
• Timing beats positioning. Like most UK breakdowns the window is late afternoon into evening, and it moves fast. Be in the target box early.

What to watch

The heat eases gradually rather than slamming shut — humid air lingering in the south keeps the storm risk alive into early next week as Atlantic systems push in. Keep an eye on the Met Office warnings page and our 5-day outlook; live radar and the targets board will catch the first cells the moment they fire.

Stay hydrated, stay safe in the heat — and have the kit ready for Sunday night.