A yellow weather warning has been issued with heavy showers and thunderstorms set to hit Northern Ireland.
The Met Office warned of possible flooding and disruption on Sunday.
The warning, from 10am to midnight on Sunday, has been issued for all six counties in Northern Ireland. Parts of England, Scotland and Wales are also affected.
The Met Office said: “Heavy showers and thunderstorms are expected to break out from late morning on Sunday, perhaps becoming quite widespread during the afternoon.
"Some places will miss the worst of these, but where they do occur, 20 to 30 mm rain could fall in a short space of time leading to some surface water flooding.
"Lightning and hail will be additional hazards. Showers and thunderstorms will only slowly ease during the evening and some could persist well into the night.”
Forecasters had already warned of cloud, rain and even thunder this weekend as the recent spell of good weather comes to an end.
Temperatures have soared recently, but the first weekend in July will be slightly cooler with occasional bright spells.
Jonathan Vautrey of the Met Office said the cloud of Friday will continue on Saturday morning.
“We have a front coming through from the south west of the UK and moving its way north eastwards overnight,” he said.
"That will bring increasing amounts of low cloud to Northern Ireland and also showers as well.”
Thicker cloud from the south on Friday night will bring some patchy light rain, and will be followed by a mild night with minimum temperatures at 13°C.
There will be patchy rain and cloud on Saturday morning.
“Some of those showers may blend together at times to produce slightly longer spells of rain, but that will start early on Saturday morning and continue through the morning,” said Mr Vautrey.
Some bright spells will develop later on Saturday afternoon and showers will clear. Temperatures could rise to 20C.
Mr Vautrey said there will be “potential for things to dry up slightly for Northern Ireland on Saturday afternoon, once that main front has passed through”.
“Still, some daytime showers will pop up in certain locations but even if it does stay dry, it will remain cloudy throughout the afternoon and into Saturday night with some low cloud clinging onto eastern coasts into Saturday evening and into the night,” he added.
It will be reasonably warm with light winds on Sunday, and generally similar to the start of the weekend.
“We’ll see more scattered showers throughout the day in general and they could turn heavy at times,” he said.
“For the morning at least, it will stay cloudy, but by afternoon it will turn to further clouds and a few brighter spells poking through.
"There’s also the potential for the odd rumble of thunder as well.”
Wind throughout the weekend won’t be “exceptionally strong” but there will be a noticeable breeze on Saturday, he added.