The historic canals of Ghent, Belgium, have been transformed by a thick layer of duckweed following an unusually hot and dry summer, creating a vivid green blanket along the medieval town’s waterways. This phenomenon, driven by record-breaking temperatures and a lack of rainfall, has attracted the attention of both locals and tourists, who have been seen relaxing by the canals amid unseasonably warm autumn weather.

Belgium experienced its hottest summer on record in 2026, a trend that has extended into early autumn. Temperatures in September have consistently exceeded 20 degrees Celsius, conditions that have allowed duckweed—a small aquatic plant typically confined to stagnant waters—to proliferate intensely across the city’s canals. Boat tour operator Davide Siddi, whose business depends on the clarity of the canals, noted that the situation had persisted for three to four weeks, an unprecedented development for Ghent.

Geert Weymeis, head of Flanders Waterways, explained that the duckweed growth is primarily concentrated in the Lys River, which originates in northern France and joins the Scheldt River running through Ghent. Under normal circumstances, the plant’s presence is limited, but the combination of warm temperatures and drought has led to an extensive spread. “This is the first time we have seen it grow on such a massive scale here,” Weymeis said.

The green coating contrasts sharply with Ghent’s historic architecture—including its medieval buildings and churches—whose waters typically attract visitors with their clear reflections. While the plant itself is harmless to humans and boat tours continue without disruption, experts warn that the thick duckweed layer can impact the aquatic ecosystem by blocking sunlight needed for submerged flora and fauna.

Weymeis added that the duckweed growth could persist for several more weeks if temperatures remain elevated, raising broader concerns about the environmental effects of prolonged heat and shifting climate patterns on regional waterways. Passersby often pause to photograph the striking green scene, which some describe as both visually captivating and a signal of ecological strain.

Ramzi Salhi, a local resident who recently took pictures of the canals, summed up the public sentiment: “It’s both beautiful to look at and a cause for concern.”