People are being urged to conserve water as the heatwave is forecast to continue for the next week at least.
Temperatures could go as high as 28 degrees today, with a status yellow heat warning still in place until Friday.
Max temps expected this week (°C):
Yesterday (Sunday) 21 to 26
Today (Monday) 24 to 27
Tuesday 24 to 28
Wednesday 24 to 30
Thursday 24 to 30
Friday 23 to 29Temperatures will be a little lower near coasts, especially the east coast due to onshore breezes.
— Met Éireann (@MetEireann) June 25, 2018
Irish Water is urging people not to water their garden or wash their car.
People are also being urged to take quick showers instead of baths, and to keep a jug of water in the fridge to cut down on having to wait for a tap to run cold.
Kate Gannon from Irish Water has said restrictions could come into force if the dry weather continues and high demand continues.
She explained: "We have a drought management team that meets every morning - so we monitor the situation daily.
"If we do see that the levels are reducing, we'll start to implement operational changes ourselves before we go to a step to restrict or cut off supply for specific periods."
She added: "We don't want to get to a situation where water levels are critical [...] So that's why we're going out now, before we get into the red... to ask people to conserve water, so we can avoid impacting those people on the edges of the network."
Pools
Meanwhile, there are calls for Lidl to pull plans to sell large pools for gardens.
The pools need up to 7,500 litres of water, and are set to go on sale next week.
The supermarket chain has said the pools contain a filter so they do not need to be drained and filled every time they are used.
Image: Lidl
However, Green Party leader Eamon Ryan said the system is already under pressure, and he wants Lidl to play its part.
He observed: "It's very tempting in this warm weather to think 'God it'd be lovely to be lounging out in a pool'. But we're running short of water.
"We could go into a long dry spell, and if we do this summer we're going to have to be really careful about how we use it. So I think Lidl should play their part - I think they should pull these pools. It's not the right time to be doing it."
