Months of torrential monsoon rainfall have led to some of the worst flooding China has experienced in modern history. It is now the second-costliest flooding on record in China and the fifth-most destructive weather-related disaster for non-U.S. countries.

At least 75 people have died just since Monday, the Associated Press reports, which brings the year’s death toll thus far to 576, according to the Chinese government. Beijing has been slammed with monsoon rainfall since earlier this week, which has flooded streets and led to the cancellation of hundreds of flights and trains. Tens of thousands of people have been evacuated.

More than 145,000 homes have been destroyed in the summer floods, Weather Underground’s Jeff Masters reports, and an incredible 21,000 square miles of farmland have been inundated so far. That’s approximately the size of Massachussetts and Vermont combined.

Last week, the government said this year’s floods have cost China more than $22 billion, which makes it the second-costliest flood on record in China and the fifth-costliest weather disaster that has taken place outside the United States, according to EM-DAT, the international disasters database managed by the government of Belgium.

The monsoon hasn’t been this bad in China since 1998, when the country’s worst weather disaster on record killed more than 4,000 people and tallied $44 billion in damage.

Heavy rain and thunderstorms wash across China every summer during the monsoon season beginning in May, but this year has been particularly devastating in part due to the presence of El Niño earlier in 2016.

Monsoon rain concentrates over China and Taiwan during the summer months along a stationary boundary in the atmosphere, locally called the mei-yu front. Large masses of thunderstorms called mesoscale convective complexes churn eastward along this front.

Researchers have noted that in seasons after strong El Niños, the rainfall that occurs along the mei-yu front is especially torrential and long-lived. That connection is clear in the data, with the floods in 1998 — also a very strong El Niño year — being the deadliest and most expensive weather disaster in China.

Rescuers in central China save villagers stranded by floods, state media reports. (Reuters)