The Status Yellow alert began at 6am on Sunday and will last until 9pm on Tuesday, with temperatures of up to 32C possible in places on Monday.
The Met Eireann weather warning stated: “On Sunday and Monday exceptionally warm weather will occur over Ireland with daytime temperatures of 25 to 30 degrees and possibly up to 32 degrees in places on Monday.
“Night time temperatures will range from 15 to 20 degrees.”
⚠️UPDATE: Status Yellow - High Temperature warning for Ireland ⚠️
Exceptionally warm weather on Sunday & Monday over Ireland, daytime temperatures of 25°C to 30°C 🌡️
• Heat stress
• High Solar UV index
• Risk of water related incidentshttps://t.co/yz9xhBqJow pic.twitter.com/1wdyd29XGm
— Met Éireann (@MetEireann) July 17, 2022
Met Eireann said there was an increased risk of heat stress, high solar UV index and water-related incidents.
It came as a man in his 60s died after getting into difficulty while swimming in Portarlington, Co Laois, on Saturday.
The incident happened at around 3.30pm at Derryounce Lake.
The man was taken from the water and brought by ambulance to Midland Regional Hospital Portlaoise, but was pronounced dead a short time later.
It is the third swimming-related death to have occurred in the past week.
Minister for the Environment, Eamon Ryan urged people to be careful near water.
“It happens every time, it’s so predictable, but so tragic for every family,” Mr Ryan told RTE.
“Let’s not make it a fourth family, destroyed, ruined, in this good weather,”
“Be careful, don’t go into waters that you don’t know how safe they are, stay close to the shore, look after each other, we don’t want another tragic loss.”
As the heatwave arrived in Ireland, Dublin City Council put contingency plans in place to protect the homeless from extreme temperatures and Irish Water reminded people to be mindful of their water usage.