Extreme UK Heatwaves in a Warming Climate

This website covers a broad range of topics that interest me - all within the general theme of sustainability and self development. Since my background is in meteorology and climate, I thought I'd put some real-life context into this sustainability business:

The world is warming. But specifically, (and closer to my home), the UK is also warming (by ~1.5C since 1884). The UK's climate is becoming warmer, sunnier and wetter. Spring 2025 was the sunniest on record, even surpassing the famous spring of 2020, which we all remember so well from the famous Covid lockdown.

By Considering the Climate and living a more minimalistic lifestyle, we can limit our impacts on the environment. We can even become carbon negative if we wish, by planting trees (there are many companies which offer this service). Electrification of our lives is crucial in this process. I want to make more people aware of this lifestyle, and the positive effects it can have on you and on the planet.

Even so, the vast majority of the developed world does not live like this, and billions more people in developing countries like China and India are demanding a better quality of life - which will consume more energy and 'stuff'. Even with current policies and mitigation of emissions, on the current trajectory the world will continue to warm over the coming decades - this will have profound consequences on the UK's climate, specifically when assessing the risk of extreme heat.

In this article published 18th June 2025, a team from the UK Met Office outline just how extreme heatwaves could be in the UK's current climate, and how the probability of extreme heat will increase further over the next 10-20 years. Essentially, the team ran 2560 simulations of the summer weather in south-east England (climatologically the hottest part of the UK), using actual observations from the 64 years between 1960 and 2023.

They found that the probability of exceeding a temperature of 40°C in a given summer is ~4.5% in today's climate, an increase of about 6 times since the 1980s. (For context, the UK's highest ever temperature was 40.3°C recorded during an unprecedented heatwave in July 2022.) And the rate of increase of this threshold being breached is increasing, meaning that years in the coming decades will have an even greater chance of seeing these temperatures. They estimate a 50/50 chance of 40°C being reached once again before 2035.

For readers in the US, a temp of 40°C may not seem that bad - after all, large parts of the USA experience these temperatures each summer. But in the UK, homes are build to work efficiently in a cool climate (brick and stone homes which absorb heat and take a long time to cool down). Buildings are designed to keep heat in. Also, air conditioning is not widespread (estimates are less than 5% of homes have it). Electricity is expensive here, and even if people wanted to install it, it's simply too expensive to run for a lot of households.

When the UK does see major heatwaves, such as in July 2022, the infrastructure is put under severe strain: railways buckle, roads start to melt and there are thousands of excess deaths (there were over 1000 excess deaths between 17-20th July 2022, during the peak of that heatwave). The point is that the UK is very vulnerable to extreme heatwaves.

The study also found that a theoretical maximum temperature of 46.6°C was possible in a 2023 climate, with suggestions that up to 2/3rds of the summer could experience heatwave conditions if the weather patterns allowed (defined when daily max temps exceed 28°C). The researchers note that current climate models tend to underestimate trends in extreme temperatures in western Europe, so it's entirely possible that these estimates are conservative - this wouldn't surprise me given that the possibility of exceeding 40°C was mooted until just a few years ago.

Remember that these tests were performed in the climate of two years ago - the climate has already warmed slightly since then, and will continue to warm over the coming years. Exactly what the future holds is unknown, but hotter summers in the UK are a certainty.

So, with this research in mind, it outlines how we must, on an international, national and individual level, do our utmost to reduce our emissions and impact on the environment (without even a mention of the positive impacts to biodiversity and the health of the planet in general).

Consume less, spend less and go electric!