A wave of heavy rain and thunderstorms is sweeping across the United Kingdom, putting large swathes of the country at risk of flash flooding and transport disruption. Forecasters at the Met Office have issued a series of yellow and amber weather warnings, with downpours expected to intensify throughout Monday, July 21. Some regions could see in just hours the equivalent of half a month’s rainfall — or more.

• United Kingdom
• Met Office

Eastern parts of Northern Ireland, including counties Antrim, Down, and Armagh, are under an amber alert until early Monday morning. Rainfall levels of 50 to 75 millimetres are forecast to accumulate within 12 to 18 hours — a significant share of the region’s average July precipitation, which typically stands at 89 millimetres. In parts of England and southern Scotland, 20 to 40 millimetres are likely to fall in the space of only two hours, posing a threat of surface water flooding and travel complications.

• Northern Ireland
• Antrim
• Down
• Armagh
• England
• southern Scotland

The period of intense rainfall is being driven by a combination of low-pressure systems and humid air masses, creating the right conditions for slow-moving thunderstorms and persistent showers. Officials have warned that these bursts of extreme weather may also be accompanied by lightning, hail, and strong winds. The Met Office cautioned that while not all areas will necessarily see heavy rain, those that do may experience rapid flooding, particularly in urban or low-lying zones.

• low-pressure systems
• lightning
• hail
• Met Office

The timing of the storms adds a measure of concern. Weeks of dry weather and elevated temperatures have hardened the ground in wide areas of England, making it less permeable and more prone to surface runoff. By mid-July, parts of the country were still recovering from a third heatwave of the summer, and some counties remained officially classified as being in drought. That combination — dry, compacted soil followed by sudden heavy rain — raises the risk of rapid flooding, even in places unaccustomed to such events.

• England
• heatwave
• drought

“There is a danger that where the rain does fall heavily, particularly over dry ground, it will struggle to soak in quickly, leading to fast build-ups of water on roads and in urban centres,” a Met Office spokesperson noted in a recorded weather update released on Sunday evening.

• Met Office

The effects are already being felt in parts of Northern Ireland, where local authorities have urged drivers to avoid flooded roads and stay alert for sudden changes in conditions. Emergency services continue to monitor flood-prone areas and have advised residents to prepare for potential power outages or travel disruption throughout Monday.

• Northern Ireland

Looking ahead, forecasters expect unsettled conditions to persist for much of the week. Showers remain likely on Tuesday across much of the UK, with a further risk of thunderstorms developing over southeastern England by midweek. While no new severe weather warnings have yet been issued for later in the week, officials caution that soil moisture levels remain high, meaning even moderate rain could cause localised flooding.

• England