The mercury looks set to rise up to 26C in a few days’ time as warmer weather turns the maps toasty red. Mid-range forecasting models from WX Charts show the warmest spot at 6pm on September 20 could be around Peterborough and Wisbech in Cambridgeshire where a balmy 26C could be reached.
The same weather map generated on Thursday (September 11) using Met Desk data shows a large swathe of England seeing 24-25C, stretching from Grimsby and Scunthorpe in the north to London in the south and Worcester to the west. Wales and western parts of England look set to be two or three degrees lower, with 20-21C across Wales and 19-23C in Devon and Cornwall, the map shows.
Another mid-range model generated by WX Charts also using GFS for the same time and date shows top temperatures of 14-15C across much of England and Wales, while East Anglia, London and South East England could see 19-21C.
The Met Office defines a heatwave as an extended period of hot weather relative to the expected conditions of the area at that time of year. While the WX Charts forecast currently only shows one day where England could reach 26C in late September, the temperature for this period is, on average 20C.
The Met Office’s long range forecast, from September 15-24, says the unsettled theme seen currently is likely to continue at first with more showers and a brisk westerly wind.
It adds there is a risk of some stronger winds and heavy rain around the middle of the week, although this looks a low risk at this time.
The forecaster says later in the period the weather may trend towards more settled and drier spells interspersed with rain and showers.
These look more likely across southern parts of the UK, but may extend to other areas at times, according to the Met Office.
It says temperatures will likely be close to average or slightly below, but if the UK starts to see more in the way of dry weather later in the period, temperatures could recover back to a little above average “at times”.
Netweather’s forecast for September 15-21 says ridges of high pressure look set to move eastwards across southern Britain, bringing a couple of days of dry sunny weather behind belts of rain moving across the country, especially England.
High pressure may extend further north towards the end of the week, bringing dry sunny weather northwards into much of Scotland, Wales and Northern Ireland.
More changeable and wet conditions are likely to persist in the north and west of Scotland for most of the week, though. Netweather’s forecast also says some strong winds are possible, especially early in the week and especially in the north and west of Britain.
Mean temperatures are forecast to be very close to the 1991-2020 long-term normal in western Britain, but about 1C above normal in the east of Scotland and England.
Below-average temperatures will be offset by unusually high sea surface temperatures around the British Isles following the record warm spring and summer, according to the forecaster.