The temperature in Derry is predicted to be similar to heat levels in Spain this week, say experts.
The Weather Company, the world's largest private weather enterprise, predicts the temperature in Derry will rise to as high as 25°C on both Thursday and Friday.
The average temperature in the North of Ireland in May is around 14°C.
The Weather Company predicts temperatures will start to rise in Derry on Tuesday (20°C) and will continue to do so right through to Friday when it is expected to be as warm as parts of Spain.
Although temperatures are predicted to be higher than normal, the good weather is not expected to last.
Rain is forecast for Saturday and it is expected to remain cloudy into the beginning of the following week.