This heatwave should be shorter lived than others so far this summer with temperatures starting to feel noticeably cooler over the weekend.
Scotland and Northern Ireland will not experience the same extreme heat as southern England, although eastern parts of Northern Ireland, southern and eastern Scotland will still see temperatures well above the heatwave threshold.
They will be notably above average for mid-August and the humidity is likely to intensify on Wednesday night into Thursday.
Some places could reach the mid to high 20s Celsius on Wednesday – when a typical August daytime temperature would generally be in the high teens to low 20s.
Western Scotland and western parts of Northern Ireland are likely to remain somewhat cooler due to cloud and occasional rain moving in from the Atlantic.
While confidence in the details remains low, this could open the door for showers and perhaps some prolonged spells of rain.
To alleviate drought though, months of above-average rainfall is needed.