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The world’s most-populated city, Shanghai, just had its hottest day in recorded history

Children cool off from hot weather in a fountain in Shanghai on Friday. (Aly Song/Reuters)

On Friday, the 24-million-plus inhabitants of Shanghai witnessed the temperature skyrocket to 105.6 degrees (40.9 Celsius), its hottest day ever recorded.

The Chinese city, which has more people than any in the world, has tracked temperatures since 1872.

Friday’s temperature extreme fits into a recent pattern of increasing hot weather.

“Shanghai is getting hotter — the previous record of 40.8 [Celsius] was set only in 2013, and eight of the 12 highest temperatures reached over the past century were recorded in the last five years, according to the city weather bureau,” the AFP reported.

The excessive heat spurred an increase in hospital visits because of heat-related illness, and the city was under a “red alert” — its first this year, and the 13th since China launched a heat alert system a decade ago.

“China has a three-tier early warning system for high temperatures: a yellow warning is issued when high temperatures above 35 degrees Celsius are predicted for three consecutive days, orange indicates a predicted high temperature of 37 degrees Celsius in the next 24 hours, and a red alert is issued when the temperature is forecast to reach 40 degrees Celsius within 24 hours,” explained, the Chinese news agency.

Much of eastern China was under the influence of a large ridge of high pressure — or heat dome. This heat dome may hold in place for the next week, meaning many more days of scorching temperatures.

This record high temperature in Shanghai is one of several all-time heat records set this summer around the Northern Hemisphere:

While these temperatures extremes have occurred, the Earth’s average temperature so far in 2017 ranks second highest in records dating back to 1880.