An Orange High-Temperature Warning has been issued for six counties.
The alert impacts Cavan, Monaghan, south Leitrim, Roscommon, Longford, Westmeath.
It will come into effect from 2pm this afternoon.
Status Orange - High Temperature warning for Cavan, Monaghan, south Leitrim, Roscommon, Longford, Westmeath
— Met Éireann (@MetEireann) July 20, 2021
This lunchtime the rest of the country will come under a status yellow high-temperature warning.
Met Eireann says the heat will continue for the week with hot conditions by day and staying very warm and humid at night.
Maximum temperatures will generally reach between 27 to 30 degrees.
Overnight temperatures won't fall below 17 to 20 degrees.
Both the orange and yellow weather warnings will remain valid until Friday.