Temperatures are set to rise this week across parts of the UK, the Met Office has forecasted, with some areas in southern England expected to reach 27°C on Wednesday, April 30.
While temperatures are expected to rise considerably, the Met Office has ruled against the prospect of a heatwave, in technical terms.
Commenting, Met Office deputy chief meteorologist, David Oliver said: “Despite media speculation, next week’s conditions are likely to fall just outside of official Met Office heatwave thresholds.
“However, this shouldn’t lead to any disappointment as many can anticipate a very fine spell of weather with temperatures reaching 27°C during the middle of the week.”
What is the definition of a UK heatwave?
According to the meteorology authority, a heatwave is defined as an extended period of hot weather relative to the expected conditions of the area at that time of year, which may be accompanied by high humidity.
UK heatwave threshold is determined when a location records a period of at least three consecutive days with daily maximum temperatures meeting or exceeding the heatwave temperature threshold, which varies per county, as seen in the map below:
The highest recorded temperature for the month of April was back in April 16, 1949, when Camden Square in London recorded 29.4°C.
Met Office chief forecaster, Matthew Lehnert said: “We are not expecting the April UK temperature record to be broken, but some locations may nudge local records.
“Often warm spells are driven by warmer air arriving from further south, but the origins of next week’s air are from Scandinavia and central Europe.
“This air mass will be warmed by compression as the high pressure begins to build, and this warmth will be boosted by daytime heating from the April sun.”
Why do heatwaves happen?
According to the Met Office, heatwaves are most common in the summer when high pressure develops across an area.
High pressure systems are slow-moving and can persist over an area for a prolonged period of time, such as days or weeks.
They can occur in the UK due to the location of the jet stream, which is usually to the north of the UK in the summer. This can allow high pressure to develop resulting in persistent dry and settled weather.
