The increasing likelihood of temperatures above 30 to 40 °C in the United Kingdom

As European heatwaves become more severe, summers in the United Kingdom (UK) are also getting warmer. The UK record temperature of 38.7 °C set in Cambridge in July 2019 prompts the question of whether exceeding 40 °C is now within reach. Here, we show how human influence is increasing the likelihood of exceeding 30, 35 and 40 °C locally. We utilise observations to relate local to UK mean extremes and apply the resulting relationships to climate model data in a risk-based attribution methodology. We find that temperatures above 35 °C are becoming increasingly common in the southeast, while by 2100 many areas in the north are likely to exceed 30 °C at least once per decade. Summers which see days above 40 °C somewhere in the UK have a return time of 100-300 years at present, but, without mitigating greenhouse gas emissions, this can decrease to 3.5 years by 2100. The United Kingdom has experienced a strong heat wave in 2019 that set a new temperature record for the country of 38.7 °C. In this study the authors show that under climate change, local temperatures are increasingly likely to exceed 35 °C and 40 °C in the next decades and, hence, summers like the one of 2019 become more frequent.