LONDON — To the casual observer, it may seem as if Britain is completely unprepared to deal with long spells of scorching-hot weather.

The casual observer would be mostly right.

The monthlong heat wave has broken records, spawned wildfires in Wales and England, spurred delays in the transportation system and given birth to names like “Furnace Friday,” as Britons tried to find ways to describe this puzzling pain.

“Shops are out of fans, ice, sun cream, ice cream, and there’s a water shortage that has left our beautiful, lush parks all parched and yellow,” said Lucy Thornton, 36, an interior designer, as she walked into a west London cafe on Friday in search of cold water.

“We’re not equipped for this,” she added, “so it feels kind of apocalyptic.”

Summer started out with unusually good weather: The rain stopped, the skies cleared, and the sun came out. Some Britons were so delighted that they canceled vacations abroad.