Northern Ireland’s current heatwave is set to end on Friday after five consecutive days of temperatures reaching 25C at Castlederg, County Tyrone. The Met Office defines a heatwave in the region as at least three consecutive days when the mercury hits 25C or higher at a single weather station.

The run of heat at Castlederg began earlier this week but is not expected to extend into a sixth day as cooler northerly winds arrive. That marks the longest heatwave since a similar spell in June of this year and remains far short of Northern Ireland’s record of 13 days, set in both 1976 and 1995.

The summer of 1976 is remembered for its prolonged heat and drought; the summer of 1995 brought four separate heatwaves to Northern Ireland, believed to be the most in any single year.

The recent dry stretch has lowered water levels at Silent Valley reservoir in Kilkeel, County Down. Apart from one or two very isolated showers, no significant rainfall is forecast until at least the middle of next week.

The UK Met Office notes that as the planet warms, extreme weather events including heatwaves are becoming more likely. Met Éireann adds that heatwaves have grown more frequent and intense globally since the 1950s, with human-driven climate change the main cause. Projections indicate that heatwaves will almost certainly increase in duration, frequency, and intensity over most land areas.

Temperatures will drop below the heatwave threshold across the island this weekend, though it will stay warm in many areas, with some cloud in the north and sunshine elsewhere.