NASA Satellite Catches Fall Colors Already Sweeping the Arctic Tundra

While much of North America endured a summer of remarkable heat, fall colors and crisp weather still felt distant across the continent in early September 2026. But autumn arrives early in the tundra and subarctic ecosystems of Nunavut, in far northern Canada: NASA's Landsat 9 satellite, using its Operational Land Imager, captured vivid reds, yellows and oranges already sweeping across the landscape near Kugluktuk on September 6 — a sharp change from an image of the same area taken on July 27, when the vegetation was still green.

The Coppermine River region is known for willow and birch shrubs, blueberries, bearberries and other low-growing tundra plants that turn red, orange and yellow each fall. A NASA and South Dakota State University analysis of seven years of satellite data found that foliage in the region begins changing in early September and peaks in mid-month, making it one of the first places on the North American continent to change color — though the peak color there can last a week or less, shorter than in many lower-latitude areas.

Leaves change color as they lose chlorophyll, the molecule plants use to make food, which also makes them appear green because it absorbs red and blue light. Chlorophyll is not a stable compound and must be continuously resynthesized using ample sunlight and warm temperatures; as autumn brings shorter days and falling temperatures, chlorophyll levels drop. As the green fades, other pigments take over: carotenoids, which absorb blue-green and blue light and make leaves appear yellow, and anthocyanins, which absorb blue, blue-green and green light and make leaves appear red.

Citizen scientists can help NASA track the changes through the GLOBE North American Phenology Campaign, observing and recording leaf color shifts each spring and fall to build long-term records of how plants respond to climate and environmental change.