The short version
- High pressure systems are driving temperatures into the mid-20s Celsius in southern England, marking a notable deviation from late September norms.
- The current warmth does not satisfy Met Office requirements for a heatwave, which mandates sustained higher temperatures over three consecutive days.
- While eastern regions remain dry and warm, western and northern areas face increased rainfall as weather fronts shift across the country.
Weather patterns across the United Kingdom are shifting toward unseasonably warm conditions for late September, with forecasts indicating temperatures will climb well above historical averages. High pressure systems are building over the region, creating a settled atmosphere that is expected to bring brighter skies and reduced rainfall to much of England and Wales. This meteorological setup suggests a temporary return to summer-like weather, although experts caution that the intensity will not reach the levels required for an official heatwave declaration.
The primary driver of this warmth is the accumulation of high pressure, which effectively blocks rain-bearing weather systems from crossing the country during the early part of the week. As a result, southern and eastern England are likely to experience drier conditions, offering little relief to areas currently grappling with drought. The stability in the air mass allows for sunshine and light winds, contributing to a gradual rise in temperatures that will feel significantly warmer than typical autumn weather.
Temperature readings are projected to peak around 25 degrees Celsius (77 Fahrenheit) in south-east England, while other parts of England, Wales, Northern Ireland, and eastern Scotland may see highs in the low 20s. These figures represent an increase of approximately five degrees above the average for this time of year. In Scotland and Northern Ireland, where cloud cover is more prevalent, temperatures are still expected to rise, reaching between 18 and 22 degrees Celsius. The exact peak temperatures will depend largely on how effectively sunlight penetrates through any remaining cloud layers.
Despite the noticeable warmth, the Met Office has confirmed that these conditions do not meet the criteria for a heatwave. Official definitions require temperatures to reach between 26 and 28 degrees Celsius, depending on the specific location, for three consecutive days. Since the forecasted highs are expected to remain in the 20 to 25-degree range, the threshold will not be breached. Nevertheless, the sensation of summer returning is likely due to the combination of higher temperatures and increased humidity, particularly as mist and fog give way to clearer skies.
The weather dynamic is not uniform across the entire United Kingdom. While eastern regions enjoy dry and warm spells, western and northern areas are facing different conditions. Rain is anticipated to move into western Scotland and the west of Northern Ireland by Tuesday. This precipitation is expected to become more substantial by Wednesday, stretching across Scotland, Northern Ireland, Wales, and western parts of England. As high pressure shifts slightly eastward, these regions will experience cooler temperatures, returning closer to the seasonal average of 14 to 18 degrees Celsius.
This warm spell occurs against the backdrop of a record-breaking year for heat in the UK. The current calendar year has already seen an unprecedented number of days with temperatures exceeding 25 degrees Celsius. Last week alone contributed significantly to this tally, helping to surpass the previous record of 89 such days set in 1959. This context highlights the broader trend of increasing frequency and intensity of warm weather events, even if individual spells do not always qualify as heatwaves under strict meteorological definitions.
Looking ahead, the warmth is expected to persist for much of the week in England and Wales, though it will begin to taper off toward the end of the period. Temperatures may drop by a few degrees but are still projected to remain above average, staying in the high teens to low 20s. The settled weather pattern is likely to continue in southern and eastern England, maintaining dry conditions that could exacerbate existing drought issues in those areas.
Beyond this immediate forecast, the outlook for the final week of September suggests a slight cooling trend, although temperatures will still hover above average. As October approaches, uncertainty increases regarding long-term patterns. Early signs indicate a potential shift toward more typical autumn weather, characterized by wetter and windier conditions. This transition marks the end of the current warm interlude and the return of seasonal variability that defines the UK's climate during the fall months.
Warm spells at this time of year are not entirely unusual, as southerly airflows can transport hot air from southern Europe or North Africa into the British Isles. However, the combination of record-breaking heat days earlier in the year and this late-season warmth underscores the changing nature of seasonal weather patterns. Residents are advised to monitor local forecasts for updates on rainfall distribution and temperature fluctuations as the high pressure system gradually weakens.
Sources behind this briefing
Go to the original reporting
- BBC News↗Temperatures forecast to hit 25C but heatwave chances fall
