As the nights grow longer and the recent arrival of Storm Agnes brings strong winds and rain, the early September heatwave may seem like a distant memory. Nonetheless, the heatwave and
consistently above-average temperatures have made it the joint warmest September on record in the United Kingdom, aligning with a broader trend of record warmth worldwide.
The UK's warm weather has continued into October. The Met Office has released data revealing that the average temperature in the UK throughout September was 15.2°C, tying it with 2006 as the warmest September ever recorded. When breaking this down to the average maximum recorded temperature, September reached 19.4°C, marking the warmest September in 127 years, sharing the top spot with 1895. For England and Wales, it was their warmest September on record.
This exceptional warmth was, in part, a result of the extensive and record-breaking heatwave at the beginning of September, during which the temperature climbed above 30°C for seven consecutive days. Additionally, the UK recorded its highest temperature of 2023 during this heatwave, a phenomenon that has only occurred four times before in the recorded climate history.
The Met Office conducted a rapid attribution study on the September warmth, indicating the potential influence of climate change. It concluded that the September 2023 mean temperature of 15.2°C would have been virtually impossible without human-induced climate change, emphasizing the impact of climate change on the recent temperature patterns.
This warming trend is not limited to the UK. France, Germany, Denmark, and Austria also experienced their warmest September on record. In France, the mean temperature exceeded the previous record set in 1949 by over a degree.
Globally, temperatures have seen a significant spike since June, with the last few months setting records by a considerable margin. Berkeley Earth, an organization tracking global temperatures, stated in their August assessment that 2023 is "virtually certain to be the warmest year on record." This trend has been partly attributed to the presence of El Niño in the Pacific, a natural weather pattern phase associated with warming that has raised global temperatures.
The extent of the global temperature rise since the summer has surprised many experts. Professor Ed Hawkins from the University of Reading noted that global temperatures in 2023 are "extraordinary" and breaking records by "shocking" amounts.
Returning to the United Kingdom, above-average temperatures have persisted into October. On the first day of October, the temperature in southeast England reached 24.1°C in Wisley, Surrey, approximately six degrees higher than the average for this time of year. This marked the warmest October day in five years and the warmest start to the month since 2011.
While the temperatures in the coming week may not reach the same heights, the weekend is expected to bring a return of warmth. On Saturday, temperatures are forecasted to widely reach the low 20s, with some parts of southeast England expected to reach the mid-20s. Nonetheless, temperatures are not expected to surpass the current October record of 29.9°C set in 2011.