Helicopters hauling buckets of water fly toward the mountains where fires burn, a thick haze periodically covers the sky, and residents have been ordered to wear masks and limit driving because of the poor air quality.

For a full week, firefighters have been battling fires in the mountains around Bogotá, Colombia’s capital, as dozens of other blazes have burned across the country, in what officials say is the hottest January in three decades.

The president has declared a national disaster and asked for international help fighting the fires, which he says could reach beyond the Andes Mountains and erupt on the Pacific Coast and in the Amazon.

Colombia’s fires this month are unusual in a country where people are more accustomed to torrential rain and mudslides than fire and ash. They have been attributed to high temperatures and drought exacerbated by the climate phenomenon known as El Niño.

Ricardo Lozano, a geologist and former environment minister of Colombia, said El Niño was a natural phenomenon that occurred cyclically, but that with climate change, “these events are more and more intense and more and more extreme.”