The Met Office has identified 22 areas across the UK that will receive no rainfall during a five-day heatwave expected in early July. According to the Met Office, a heatwave occurs when a location records at least three consecutive days with daily maximum temperatures meeting or exceeding a threshold that varies by region, ranging from 25°C to 28°C.
Heatwave Definition and Thresholds
The threshold for a heatwave is 25°C in Scotland, Northern Ireland, Wales, much of Northern England, and parts of the South West. In the Midlands, East Anglia, and parts of Southern England, the threshold is between 26°C and 27°C, while Greater London requires 28°C.
The Met Office explains that heatwaves are most common in summer when high pressure develops across an area. High pressure systems are slow-moving and can persist for days or weeks. They occur in the UK due to the location of the jet stream, which is usually north of the UK in summer, allowing high pressure to develop and result in persistent dry and settled weather.
Timeline of the Heatwave
Friday, July 3, will see warmer weather than anticipated, with temperatures rising over the weekend. The first signs of the heatwave will appear on Saturday, July 4, around 4pm, though these temperatures will not yet meet the official heatwave criteria. However, Greater London, the Midlands, and parts of the North East will be just one degree below the heatwave threshold.
On Sunday, July 4, at 4pm, temperatures will align with heatwave conditions. London is expected to reach 28°C, while Southampton will hit 27°C. The Met Office predicts heatwave conditions from Sunday to Thursday, July 7.
Areas Affected by the Heatwave
The 22 areas set to experience heatwave conditions on Sunday include: London, Boston, Southampton, Rochester, Cambridge, Milton Keynes, Banbury, Ipswich, Hereford, Peterborough, Yeovil, and Exeter.
From Monday onwards, additional areas will reach heatwave temperatures, with highs of 30°C expected. These areas include: London, Boston, Southampton, Rochester, Cambridge, Milton Keynes, Banbury, Ipswich, Hereford, Peterborough, Yeovil, Exeter, Plymouth, Nottingham, Birmingham, Hull, Sheffield, Stoke-on-Trent, Derby, Lincoln, Bridlington, and Norwich.
Peak Temperatures and Duration
The heatwave is expected to last until Thursday, July 7. London is projected to reach 30°C on Thursday, while other areas such as Oxford, Reading, and Rochester will top out at 29°C. The Met Office has also noted that 22 areas will receive no rainfall at all during this period, emphasizing the dry conditions.
