Temperatures are set to soar to 30C in parts of the UK this week before unsettled weekend weather brings heavy rain and thunderstorms.
The Met Office has issued a yellow thunderstorm warning for much of Northern Ireland from 11am until 8pm on Thursday.
Heavy showers and thunderstorms may cause disruption, particularly to travel, with between 30mm and 40mm of rainfall expected over a few hours, the Met Office said.
Across other parts of the UK temperatures will climb to 28C with a chance of 29C on Thursday, before peaking at a potential 30C in London on Friday, Met Office meteorologist Jonathan Vautrey said.
Unsettled weather is then forecast to spread across more of the UK over the weekend, as temperatures start to slowly drop.
Mr Vautrey said: "We're starting to see south westerly winds come in, that's bringing in hotter and more humid conditions, particularly in southern areas, we are going to see temperatures climbing again.
"There is the potential for 30C around the London region by the time we reach Friday, other areas around south east England will push towards high 20s.
"Average temperatures in July for the south east is around 23C, so it will be about 5C above average.
"On Thursday it will probably creep up to around 28C in London, maybe 29C in more central England. Friday is looking to be the peak of the current hot spell.
"This heat is not going to be as widespread as what we've just come out of, areas to the north aren't going to be seeing the same highs.
"The heat we had last time was home grown, it wasn't that humid, but because this heat is coming in from the south westerly direction, it is more humid. It's going to be feeling more sticky."
The weather is set to turn unsettled through the weekend, with a chance of some heavy showers and thunderstorms across the UK, but detail on that is currently low, Mr Vautrey said.
Weekend high temperatures are still expected to reach 28C or 29C on Saturday and 25C on Sunday.
There is a “small probability” a localised area manages to get the three-day category for a heatwave this week, but for most people it will be more of a “hot spell”, Mr Vautrey added.
(PA) Note: This article has been edited with the help of Artificial Intelligence.
