Fires are spreading through the central and eastern Amazon rainforest as an El Niño-driven drought leaves Brazil's forests primed to burn, according to NASA Earth Observatory. On Oct. 12, heavy smoke blanketed Manaus, a city of more than 2 million people, pushing fine-particle pollution above 135 micrograms per cubic meter.

NASA scientist Douglas Morton described the Amazon as the next stage in a chain that began with fires in Indonesia, saying the region is seeing "the second domino in the cascade fall." The pattern follows the same sequence seen during the strong El Niño of 2015 and 2016 and again in 2023.

The fires are already affecting daily life. Amazonas state has declared a fire emergency in 36 municipalities, Manaus has closed schools and canceled outdoor events, and NASA scientists expect burning to continue until the rainy season arrives in December or January.

From Indonesia's Haze to Brazil's Rainforest

The chain began on the other side of the world. Since August, drought and peat fires in Indonesia have sent smoke over entire islands, and Nature World News reported this week that Indonesian haze closed schools for about 2 million Malaysian students.

El Niño's effects build over many months, and drought linked to the current event has now reached the Amazon. Brazil's National Institute of Meteorology reported that Manaus received 95% less rain than normal in August and 60% less in September, according to NASA.

Fires are concentrated in forests around Manaus and Santarém and extend toward the mouth of the Amazon River in Pará and Amazonas states. NASA's image of the smoke was captured on Oct. 12 by the MODIS instrument on the Aqua satellite.

People, not lightning, start nearly all of these fires. Lightning causes less than 1% of fires in the Brazilian Amazon, NASA said, and the large blazes began as management burns on pastures and fields before escaping into the forest understory.

Emergency Declared Across 36 Amazonas Cities

Amazonas Governor Roberto Cidade declared the fire emergency on Oct. 10, covering Manaus and its metropolitan area, the south of the state and several river towns, including Itacoatiara, Parintins and Tefé, according to The Rio Times. Brazil's federal government recognized the decree within hours, allowing the state to request federal funds.

Satellite hotspot counts in Amazonas jumped to 3,726 in September, nearly four times the 942 recorded in September 2025, the outlet reported, citing figures compiled by Brazilian news site G1. These counts are preliminary and can undercount fires hidden by smoke or forest canopy.

That undercounting is a real problem. Shane Coffield, a University of Maryland researcher working with NASA Goddard, estimated about 40% more fires in the Santarém area than standard active-fire counts show, according to NASA. His team identified roughly 50 to 70 uncontrolled fires in that region alone.

Air quality has swung sharply. A state sensor in Manaus recorded about 209 micrograms per cubic meter of fine particles early on Oct. 10, while readings in Itacoatiara spiked far higher, The Rio Times reported. Manaus recorded 82 urgent-care visits linked to smoke between Oct. 1 and 8.

Smoke, Health and the Forest Itself

The greatest health risk falls on children, older adults, pregnant people and anyone with heart or lung disease, groups that are most sensitive to fine-particle smoke. Residents in river towns with limited health care face added challenges in getting treatment, and many communities depend on boat travel that smoke and low visibility can disrupt.

The forest faces its own long-term damage. Morton noted that the same forests burned in 2015 and 2023, and earlier fires left partly charred trees that make the remaining forest more flammable. Some future fires may burn more intensely as a result.

Morton also urged people in the region to avoid burning entirely this year. "This really is the year for people to avoid burning at all costs," he said in the NASA report. Brazilian officials have deployed state and federal firefighters, with Ibama reporting more than 200 fires extinguished since the critical season began, according to The Rio Times.

A Global El Niño Story With More Fires Ahead

The cascade is not over. NASA expects later fire waves in Roraima, northern Pará, Amapá and parts of Venezuela, Guyana and Suriname, with drought and fire risk in the southern Brazilian Amazon and Paraguay expected to peak around August and September 2027.

For U.S. readers, the Amazon fires are part of the same El Niño that is shaping weather patterns from Hawaii to the Atlantic, as Nature World News reported in September. Large tropical forest fires release carbon that the forest would otherwise store, which is one reason scientists track them closely as part of global climate data.

Travelers headed to Manaus or the Amazon region should check local air quality forecasts and airline notices, carry well-fitting N95 masks, and follow guidance from Brazilian health and civil defense authorities. People with asthma or heart conditions should talk with a doctor before traveling to smoke-affected areas.

Brazil's forest fire season typically eases when rains return, and NASA expects relief in the Manaus and Santarém regions by December or January. Until then, satellite updates from NASA and Brazil's national space agency will show whether the burning slows or spreads.

The bottom line is that a single El Niño is now driving fires on two continents. Indonesia's haze was the first warning, the Amazon is the second, and scientists say more fire-prone regions could follow through 2027.

What Readers Want to Know

Where are the Amazon fires burning?

Mainly in forests around Manaus and Santarém and toward the mouth of the Amazon River, in Brazil's Amazonas and Pará states.

Why is the Amazon burning now?

An El Niño-linked drought cut Manaus rainfall by 95% in August and 60% in September, and fires set on pastures and fields escaped into dry forest.

What does the second domino mean?

NASA scientist Douglas Morton used it to describe a chain of El Niño-driven fires that started in Indonesia and has now reached the Amazon.

How bad is the smoke in Manaus?

Fine-particle pollution topped 135 micrograms per cubic meter on Oct. 12, and schools and outdoor events were canceled.

How long will the fires last?

NASA expects fires near Manaus and Santarém to continue until the rainy season begins in December or January.

Does this affect the United States?

Not directly through smoke, but the fires are part of the same strong El Niño influencing global weather and are tracked as part of global climate data.