The working national definition of a heatwave is five (5) consecutive days or more with maximum temperature over 25 degrees Celsius (> 25 °C). Using this definition, official national heatwaves have not yet occurred during 2019.
With the heat island effect, day-time temperatures were high with warm humid nights at Phoenix Park, Co Dublin. There were two days over 25 °C during July 2019. For more detail on this and the current extreme temperatures in Europe, please see our report linked here.