Met Office brings forward Northern Ireland thunderstorm warning forecasting heavy rain to arrive earlier

The Met Office has brought forward the start time of its yellow weather warning for Northern Ireland after heavy rain arrived earlier than first forecast.

The updated warning is now in force from 9.15am until 9pm on Tuesday, 4 August 2026, with forecasters warning that heavy showers and thunderstorms could cause disruption to transport and outdoor events.

Warning updated as rain moves east

The Met Office said the warning was revised after a band of heavy rain developed across western parts of Northern Ireland, moving slowly eastwards during the morning before more widespread showers develop later in the day.

The updated forecast means the period of potential disruption begins almost three hours earlier than originally advised.

Heavy downpours, hail and gusty winds possible

Forecasters say showers will become heavier and more widespread through Tuesday morning, with some turning thundery during the afternoon.

Although some places may escape the worst of the weather, slow-moving storms could bring 20-30mm of rain within one or two hours, creating a risk of localised surface water and difficult travelling conditions.

The heaviest showers may also be accompanied by strong, gusty winds and hail.

Travel and outdoor events may be affected

The Met Office is warning that the unsettled conditions could lead to disruption on roads and affect outdoor events across Northern Ireland.

Drivers are being encouraged to take extra care, allowing additional time for journeys where heavy rain reduces visibility or causes standing water on roads.

As is often the case with summer thunderstorms, conditions are expected to vary considerably across the region, with some communities experiencing torrential downpours while others see little or no rainfall.

Conditions expected to improve this evening

The showers are forecast to gradually ease from western areas during the evening before the warning expires at 9pm on Tuesday, 4 August 2026.