Heat will persist across the UK and northern Europe this week, potentially boosting demand for energy to keep buildings cool.

London is set to reach 29C (84.2F) on Tuesday, while Oslo will push above 28C later in the week, according to a forecast from Maxar Technologies Inc. Southern regions look cooler, with Madrid at no more than 23C on Tuesday.

The UK’s hot spell has prompted health alerts, with the nation’s Health Security Agency issuing amber warnings — the second-highest level — for some parts of the country. Over the weekend, temperatures peaked at 32.2C in Chertsey near London, making Saturday the warmest day of the year so far in England.

In anticipation of higher energy demand, the UK’s grid manager asked one power-station operator to warm up a coal-fired unit Monday to help stabilize the network amid a drop in wind power. The Uniper SE-owned Ratcliffe generator will connect to the grid later if needed.

Scotland and Northern Ireland also saw the highest temperatures so far this year, with readings of 29.8C and 25.3C, respectively, at the weekend. Much of the UK has since seen thunderstorms, with parts of London getting the first rain in almost four weeks.

Next week, temperatures are set to stay above the seasonal norm in some areas of Europe including Britain, northern Germany and northwest France, Maxar said.

• Northwest Europe weather forecast for the next two weeks: