By midcentury, troops could face an extra month of heat-index temperatures above 100 F every year, the Union of Concerned Scientists found.
This shows the UK's average temperatures in selected years. All its hottest years since 1884 have occurred this century.
Watch for the signs of heat illness in scorching summer temperatures.
June 2019 has just been confirmed as the hottest month ever on record, according to Copernicus.
Portugal’s Met Office has retracted its prediction that temperatures in the country could reach 50ºC — the hottest ever recorded on mainland Europe — this week, drastically revising the forecast down by 10 degrees.
Thousands across the world plunged into icy waters to welcome in 2018.