Satellite observations show a marked rise in fire activity and smoke across parts of the central and eastern Amazon beginning in September 2026, according to a NASA Earth Observatory report published October 15. The affected area extends from around Manaus and Santarém toward the mouth of the Amazon River.
An image captured by the MODIS instrument on NASA’s Aqua satellite on October 12 showed smoke from fires on both sides of the Amazon River. In Manaus, officials reported very poor air quality that day, with PM2.5 readings above 135 micrograms per cubic meter. The report said schools closed and city events and children’s sports leagues were canceled amid warnings about unhealthy air. The city is home to more than two million people.
NASA Earth system scientist Douglas Morton described the fires as part of a recurring tropical pattern associated with El Niño-related changes in rainfall. In a 2017 study with colleagues, Morton examined a sequence in which drought and peat fires in Indonesia were followed by elevated fire activity in the Amazon. He said the pattern also appeared in 2023. The current sequence began with drought and fires in Indonesia in August, followed by increased activity in the Brazilian states of Pará and Amazonas.
Morton expects additional fire activity farther north in November and December, including in Roraima, northern Pará and Amapá, as well as parts of Venezuela, Guyana and Suriname. He said fire risk could peak later, around August and September 2027, in southern areas of the Amazon in Brazil and Paraguay. These are projections attributed to Morton, not reported outcomes.
The NASA report says drought has left forests especially vulnerable. Brazil’s National Institute of Meteorology reported that rainfall in Manaus was 95 percent below normal in August and 60 percent below normal in September. Morton said lightning starts less than 1 percent of fires in the Brazilian Amazon, and that most of the fires now burning were started by people. He described many large fires as beginning with land-management burns, such as clearing vegetation for pasture or fields, then escaping into dry forest understory.
Shane Coffield, an assistant research scientist at the University of Maryland working at NASA Goddard, estimated that 50 to 70 uncontrolled fires were burning in the Santarém area. He is using observations from the VIIRS satellite instrument to look for fires that may not appear in standard NASA fire-monitoring products. Coffield said his team identified about 40 percent more fires around Santarém than active-fire counts in NASA’s Fire Information for Resource Management System, or FIRMS.
Coffield noted that smoke, clouds and tree cover can prevent satellites from detecting the heat signature of fires, particularly lower-intensity fires moving through forest understory. He said that on some very smoky days, MODIS and VIIRS register few detections even though fire activity is continuing. The team plans to share candidate fire locations with MapBiomas, a network that maps fire and land-use change in the Amazon.
Morton warned that repeated burning may worsen damage to forests, where many species are not adapted to fire. He said forests previously burned during the 2015–16 and 2023 El Niño periods are burning again, and that earlier damage could leave remaining trees more vulnerable. He expects fires near Manaus and Santarém to persist until the rainy season, which he placed in December 2026 or January 2027. He urged people to avoid setting fires during the current conditions.
