“During the daytime of August 23, most portions of the ... Jianghan Region, eastern Southwest China, and western Jianghuai Region will be exposed to [a] heat wave of over [95 degrees],” read the bulletin. Temperatures of 98-102 degrees “will grip Hunan, Jiangxi, [the] eastern Sichuan Basin, northwestern Fujian, and northern Guangdong and Guangxi.” Hunan province alone has a population of 67 million.
That would be the equivalent of all of the West Coast and New England baking in triple-digit heat. Factoring in widespread tropical dew points in China between 70 and 74 degrees, that yields a “feels like” temperature of 109 degrees. According to the International Energy Agency, 60 percent of Chinese households have air conditioning — primarily only in urban areas. That’s about a third less than in the United States.
Changsha, the capital of Hunan province, is expected to hit 99 degrees on Saturday and Sunday; their average this time of year is in the upper 80s. To the west in Sichuan province, Chongqing could hit the century mark Saturday, Sunday and Monday. For an episode to technically be classified as a heat wave, it must feature three consecutive days of 90-degree temperatures or greater. Some cities in China could see three consecutive hundred-degree days instead.
The heat extends west toward Chengdu, its periphery banked against the eastern foothills of the Tibetan Plateau. Chengdu, a city known for its world-famous “hot pot,” will be pretty hot itself this weekend. They’re set to peak at 95 on Sunday, 14 degrees above average. Laos, Cambodia and northern Vietnam will also feel the heat dome’s effects.
By Monday, the heat consolidates and shunts east. That puts big-name cities closer to the coast under its sweltering influence. Hangzhou is forecast to hit 99 degrees Monday and Tuesday, while Shanghai, an hour train ride away, will peak in the mid- to upper 90s both days. Wuhan will be between 98 and 100, as well. Around that same time, a lobe of heat is set to break off and meander toward Mongolia.
The heat will bring an increase in ground-level ozone; ozone is “good up high, but bad nearby,” sparking health issues when it develops near the surface. Hot temperatures speed up ozone-producing chemical reactions. At the same time, the stagnant air mass will allow particulate matter to gather.
Despite late August and September being the best months for cleaner air in China before the winter coal-burning begins, this weekend will be an exception as Air Quality Indices climb into the “extreme” category. If you’re looking for a visual, imagine riding in a comfortable SUV. Inside that volume of air, there would be roughly a penny’s weight of metallic dust matter swirling around, similar to a carcinogenic pollen.
Climate change is increasing the odds of heat waves around the globe, and is also making them more severe. Studies of heat events in the United States, Europe, Japan and elsewhere have tied them in part to climate change. One study of a July 2017 heat wave in central China found that climate change has drastically increased the odds of such an event, which used to be rare before the addition of huge amounts of greenhouse gases into the atmosphere.
Andrew Freedman contributed to this report.