Yellow thunderstorm warning issued for Northern Ireland with flash flooding possible

A yellow thunderstorm warning for Northern Ireland is in force from 12 noon until 11.59pm today, Wednesday 19 August 2026.

Heavy showers could bring 15mm to 20mm of rain in less than an hour, while some locations could see up to 30mm in a couple of hours.

Flash flooding, difficult driving conditions, hail and lightning are all possible.

Heavy showers and thunderstorms could cause flash flooding and travel disruption across Northern Ireland today after the Met Office issued a yellow weather warning.

The yellow thunderstorm warning for Northern Ireland came into force at 12 noon on Wednesday 19 August and remains active until 11.59pm tonight.

Residents can check the latest warning information on the Met Office UK weather warnings page.

All six Northern Ireland counties covered

The warning covers:

• County Antrim
• County Armagh
• County Down
• County Fermanagh
• County Londonderry
• County Tyrone

The warning was issued by the Met Office at 9.34am on Wednesday 19 August 2026.

Heavy thunderstorms moving across Northern Ireland

A band of heavy showers is expected to move across Northern Ireland from west to east during the late morning and early afternoon.

Further slow-moving heavy showers and thunderstorms are expected to develop later in the day.

Rainfall is expected to be the main hazard.

The Met Office says around 15mm to 20mm of rain could fall within an hour or less.

A few locations could receive 25mm to 30mm in a couple of hours.

Hail and lightning are also likely in some places.

The latest regional forecast is available on the Met Office Northern Ireland forecast page.

Yellow thunderstorm warning: what could happen?

The Met Office says the weather could lead to:

• Difficult driving conditions caused by spray or standing water
• Hail affecting some roads
• Longer journey times by car and bus
• Flooding affecting some homes and businesses
• Possible damage caused by lightning
• Delays to train services
• Short-term disruption to electricity or other services

The Met Office has classified the warning as having a medium likelihood and low impact.