Northern Ireland is set to experience its third heatwave this year, just four weeks after heatwave criteria was met in July.
According to the Met Office, temperatures must reach 25C or above for at least three consecutive days for a heatwave to be declared.
Thermometers climbed to 25.2C in Derrylin, in County Fermanagh, on Monday afternoon with similar, if not warmer, conditions expected on Tuesday and Wednesday.
The average maximum temperature for Northern Ireland in August is 18.3C.
After a cloudy start to the week on Monday, more sunshine is expected on Tuesday and Wednesday, allowing temperatures to climb to 25C or higher more widely inland.
While not as warm, coastal areas are also likely to see highs reaching the low 20s.
In the Republic of Ireland, Irish weather service Met Éireann is expecting temperatures close to 30C in parts of the midlands, while heat health alerts have been issued in parts of Great Britain.
Temperatures are expected to dip by a few degrees on both Thursday and Friday before increasing again, quite widely, into the mid-twenties at the weekend.
