It was one of the hottest days of the year in Northern Ireland today (Wednesday), and the hottest of the year in Great Britain.
The highest temperature in the Province was at Aldergrove, which reached 25.4 Celsius (77.7F), but this was not as high as the 26.2C (79F) to which the mercury rose in both Lough Navar Forest Fermanagh and Castlederg on Friday May 26, during the bank holiday weekend.
However, in England today it was not only the hottest day of the year so far, it was the warmest June day since 1976. Heathrow in west London rose to 34.5C (94.1F), the highest for the month since the 35.6C (96F) in Southampton on June 28 1976.
The 40-year high – which is the hottest summer solstice on record – has been recorded as parts of Britain swelter in the fifth consecutive day with temperatures above 30C (86F).
But the hot spell is set to come to an end, as a cold front sweeps across the UK overnight. In Northern Ireland, tomorrow (Thursday) it will still be relatively warm but cooler as an Atlantic influence begins to come in.
There will be some rain coming in during the evening. On Friday it will be less warm still in Northern Ireland.
In Great Britain the hottest prolonged spell in June since the drought summer of 1976 will be replaced by heavy rain and thunderstorms in places. Parts of southern Scotland, northern England, north Wales and the Midlands have weather warnings in place for Wednesday evening.
The Met Office warned of the potential for torrential downpours, frequent lightning, very large hailstones and strong gusts of wind, which could lead to localised flooding and temporary disruption of power supplies.
Chief meteorologist Steve Willington said: “The high pressure that has dominated our weather of late is starting to move away, allowing fresher air in from the west.
“A cold front that will pass through the UK will mark an end to the hot spell of weather in the south and bring cloudier skies and lower temperatures.”
The sweltering temperatures have seen “unprecedented demand” for ambulance services in London, with people fainting, collapsing and becoming unconscious in the heat.
Patients calling for non-emergencies are likely to wait four hours for an ambulance, London Ambulance Service warned.
On Monday, London Ambulance Service call handlers answered 6,613 emergency calls, compared with 4,695 the week before - a 41% increase - and the service warned this was expected to continue while the heatwave lasted.
Peter McKenna, deputy director of operations, said: “Our crews are extremely busy.
“On Monday we attended 20% more seriously ill and injured patients than the same day last week and we’ve also been involved in a number of high-profile major incidents.”
Medical director Dr Fenella Wrigley said: “We see an increase in calls because people can forget to stay hydrated and the heat can exacerbate heart and breathing conditions.
“We are getting calls from people who do not need an ambulance – for minor sunburn, heat rash, hayfever.
“These can be dealt with by a pharmacist. If you call us for something minor, you may experience a long wait.”
Youngsters were urged not to go swimming in lakes, rivers and reservoirs during the hot weather, following the deaths of two teenagers in separate incidents.
A 16-year-old boy died at a reservoir in Rochdale, Greater Manchester, on Monday, while a 15-year-old boy died after going into a lake with friends in the Pelsall area of the Black Country, in the West Midlands, on Tuesday evening.