Many of those areas bathed in sunshine yesterday finished today with cloudy conditions and the occasional spot of rain after a promising start to the day.
It came after NI recorded its highest temperature for the year of 31.1 degrees in Derrylin, Co Fermanagh.
On a night when the UK recorded its highest ever average minimum overnight temperature of 25.8 at Kenley in south London, in NI the highest overnight average yesterday had been 18.8 degrees at Killylane in Co Antrim.
But it doesn’t look set to continue after today’s cooler downturn.
“If it’s any consolation it’s been raining in parts of England too,” said Met Office meteorologist Matthew Box today, before breaking the news that yesterday’s high could be as good as it gets for Northern Ireland this summer.
“For the UK it’s going to be a gradual change to cooler conditions. For Northern Ireland you had Monday and now you’re going to see a gradual transition to cooler, or more normal summer air temperatures.”
Asked if there was a chance of another heatwave, and, if so, will it reach Northern Ireland, Matthew said: “We’ve had this pulse of very extreme weather, we exceeded the 40 degree threshold in the London area, but over this week we’re going to see a gradual change to the normal weather you’d associate with summer in the UK.
“It seems unlikely at the moment that we’ll see temperatures get back up to what we’ve been experiencing this month for the rest of July going into August.”
Shane McKee joked on Twitter: “Turns out the heatwave is another victim of the Northern Ireland Protocol. Weather border in the Irish Sea.”