A potential heat wave threatens the south and east of the UK next week, just as the meteorological calendar moves into autumn.

With temperatures expected to rise above 25C (77F) for several days, that will “bring some locations into the realm of heat wave conditions,” the country’s Met Office said in a statement on Friday. The mercury is forecast to reach 28C in London on Thursday. Most places in southern England will see the hottest days since June or early July.

While the UK has experienced two months of unseasonably cool and unsettled weather, the Northern Hemisphere has faced searing heat from China to California. Fossil fuel emissions are warming the planet, triggering extreme weather from flooding in India and the US to wildfires in Greece and Canada. July was the world’s hottest month on record.

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Temperatures are rising in the UK because the so-called jet stream is shifting north, allowing a build-up of high pressure that’s being amplified by former tropical cyclone Franklin.

A heat wave is when there are at least three consecutive days with daily maximum temperatures meeting or exceeding the long-term daily maximum levels, according to the forecaster’s website. The hot weather will potentially boost demand for energy to keep buildings cool.