In the middle of the day on Monday, the sky above São Paulo, Brazil went dark.

The city, along with parts of the Brazilian states of Mato Grosso and Paraná, was blanketed by smoke from wildfires raging in the Amazon, according to local news reports.

Earlier this month, Amazonas (the largest state in Brazil) declared a state of emergency over the rising number of forest fires, reported Euro News. Fire season in the Amazon is just beginning—it runs from August through October, with its peak coming in mid-September, and the smoke is already so bad that it can be seen from space

Last week, NASA released satellite images showing the patchwork of fires and smoke in Brazil. Citing the Global Fire Emissions Database, NASA noted that though current fire levels are slightly below average compared to the last 15 years, they are higher in some states, such as Amazonas and Rondônia.

“The state of Amazonas, in particular, has seen well above average daily fire activity through August so far,” said Mark Parrington, a senior scientist working on wildfire emissions at the European Center for Medium-Range Weather Forecasts.

According to Parrington, fires in the Amazon release an average of 500-600 megatonnes of carbon dioxide over the course of a typical year. In 2019 so far, they’ve already released 200 megatonnes of the greenhouse gas. According to the Global Fire Emissions Database, 8,668 fires have been detected in Amazonas as of Monday. That exceeds the past few years, and falls just short of the 2016 high of 8,836.

Satellite imagery has tracked the movement of the smoke, which completely filled the air in São Paulo. Gustavo Faleiros, an editor at the environmental news group InfoAmazonia, said in an email that the air quality was even worse in the countryside than in the city.

“Countryside residents started complaining about the wildfire smoke, because the air used to be clean there and now the city is full of smoke and ashes,” Alberto Shiguematsu, a São Paulo resident who tweeted about the smoke, said.

According to Shiguematsu, the sky went “really dark” around 3:15 PM yesterday. He said that in his ten years of living in São Paulo, he’s never seen wildfire smoke like that. He’d read that there were fires in the Amazon, but didn’t think he’d be affected.

“The smoke coming here, in São Paulo, thousands of kilometers away? That hit me by surprise,” he said.

The news of these fires comes amidst reports of increased deforestation under far-right president Jair Bolsonaro, which has prompted protests at home and international concern. While the smoke from the fires threatens the health of those living nearby, more fires represent an added stressor for the Amazon rainforest as a whole.

The humidity of the Amazon has, in the past, protected it against massive fires, but drought, deforestation, and agriculture could make fires so common that they would completely alter the landscape, a 2014 study warned. According to a blog post for InfoAmazonia, Brazil’s National Institute for Space Research predicts that rainfall in the central and northern Amazon will be 40 to 50 percent below normal in the next three months.

“There is a direct relationship between increased burning and the growth of deforestation,” Faleiros wrote in the blog post. “Among the 10 municipalities that recorded the largest burnings in 2019, seven are also on the list of municipalities with the highest number of deforestation warnings.”