On a cold day in early October, Nabiha Bilgrami boarded the free shuttle bus to Gatineau Park with her friends — an annual trip they make each year the region-wide Fall Rhapsody celebrating the changing colours of the forest.
However, this year, Bilgrami noticed something odd as the shuttle approached the park.
“It’s like the colors weren’t as vibrant,” Bilgrami said. “A majority of the trees were still green.”
Bilgrami wasn’t the only visitor to notice the lag in fall colours across the city. Hossein Bonakdari, an engineering professor from the University of Ottawa, said there was a significant delay in the seasonal change of colours this fall.
“Observations across North America indicate that the onset of fall colour is shifting later by several days to weeks,” he said. “Climate change is reshaping the timing and brilliance of fall foliage across Eastern Canada, including Ottawa.”
Bonakdari says this delay can be attributed to an unusually warm season.
“The intensity and duration of fall colours are highly sensitive to weather variables,” Bonakdari added. “Trees rely on cooler temperatures and shorter daylight to trigger fall colors. Warmer fall weather delays this process.”
September and October 2025 saw record-breaking heat across Ottawa, with temperatures regularly above 25C and heatwaves stretching late into the season. This year saw the hottest weather on Oct. 19 since the 1960s, Environment Canada data shows.
The heat also delayed the peak of the Fall Rhapsody. Bonakdari, who specializes in climate change and sustainable development, said warmer weather also weakens trees, leading to muted colours and premature leaf drop.
“[Fall colours] will become less vibrant overall, particularly in urban and low-elevation areas where nighttime temperatures remain elevated due to the urban heat island effect,” he said.
Climate change is reshaping the timing and brilliance of fall foliage across Eastern Canada, including Ottawa.
Hossein Bonakdari, University of Ottawa engineering professor
Environment Canada describes the Urban Heat Island Effect as a phenomenon where cities get hotter than rural areas because concrete surfaces and dark roofs radiate heat.
Despite the delay, fall colours did arrive in time for last-minute visitors. In an email to Capital Current, Strategic Communications Advisor Maryam El-Akhrass for the National Capital Commission (NCC) wrote that Ottawa’s Fall Rhapsody drew many visitors to Gatineau Park throughout September and October. The record-breaking temperatures that landed on October weekends increased traffic to the park.
“Our observations on site show that the final weekends of September and weekends in October have been among the busiest, especially with the beautiful and mainly mild weather we have experienced,” she wrote.
Nathan Adolphe, president of Carleton University’s Photography Club, said the delay was convenient for their annual photo walk in Gatineau Park. Because of scheduling conflicts, Nathan said the club had to hold the event later than expected in October.
“I was getting kind of nervous, to be honest. Usually by Nov. 1st, the leaves are gone,” Adolphe said.
“We were very lucky that the leaves were pretty much still in full color, considering how late we went in the season.”
The regular sunshine throughout Ottawa and the shortening days helped keep Gatineau Park’s trees vibrant, the NCC says.
“The brightest fall colours often follow a stretch of warm, sunny days and cool nights,” El-Akhrass added. “Sunny days boost the overall pigment concentration, resulting in brighter colours.”
Bonakdari says the vibrant falls that draw crowds will not always be guaranteed. He anticipates the fall season shifting in future years if current warming trends continue.
“As warming progresses, the beauty of fall may not disappear, but it will change — arriving later, lasting for a shorter duration and showing greater year-to-year variability,” he said.
The NCC anticipates climate change will have a measurable effect on the region, too. Last year, the NCC approved its first Climate Adaptation Plan to help mitigate the effects of climate change. The plan proposed 35 actions to implement across the National Capital Region, such as the protection of green spaces, including Gatineau Park.
“In Gatineau Park, the NCC will continue to adapt its strategies and programs to foster its resilience to climate change, such as rehabilitating our trails to be less prone to flooding and erosion,” El-Akhrass wrote.
Bonakdari hopes these adaptations towards climate change will continue across the region: “Understanding these shifts is critical not only for tourism and recreation planning, but also as an indicator of long-term forest resilience in a changing climate.”
