For much of the year, Britain is wet and dreary, more mystery novel than sparkling beach read. Come summer, though, Britons can feel a bit smug. While Americans sweat and swelter, Brits enjoy warm days and sweater-weather nights.

At least that's usually the case. But not this year.

Britain is in the throes of the longest heat wave since 1976. Average summer temperatures usually hover around 78 degrees. In London, it stays slightly cooler, hitting the low 70s during the day and dropping into the 50s at night. This year, it's been nearly 10 degrees hotter, with spikes well into the 90s. It's been unusually dry, too — just two inches of rain have fallen between June 1 and July 16, making it the driest summer on record.

This week has been especially sweaty. On Thursday, temperatures hit 96.8 degrees in London. It's so hot that train routes were temporarily shuttered over fears the tracks would buckle. So-called Furnace Friday is supposed to be even hotter, hitting 101 degrees.

And experts say the heat will last at least through early August. The Heat Health Watch Service, run by the Met Office and Public Health England, has issued a warning, urging people to stay inside and drink plenty of fluids. Prime Minister Theresa May has urged people to stay out of the sun through Friday, when temperatures are expected to hit 93 degrees.

The weather has been so hot and dry that it has turned Britain from green to brown. Satellite images released by the Met Office, Britain's national weather service, show just how dramatically the weather has changed the country's topography.

In addition to browned fields and crop damage, the warm, dry weather has been blamed for wildfires in northwestern England and a ban on sprinklers in Ireland.

There have been some unexpected upsides. The dry conditions exposed a “drowned village” in a reservoir in Dartmoor, Devon. The valley was flooded in 1898, experts say, submerging village walls, a farmhouse and a bridge. In Wales, researchers uncovered an early medieval cemetery and a prehistoric Roman farm. The Independent newspaper described it as a “gold rush” and “near-unprecedented bonanza” for archaeologists.

A report from Britain's Met Office suggests that climate change will make heat waves more frequent and severe.