By Ian Black, CBC News Ottawa, October 26, 2017
It's almost November, but many parts of Ottawa are looking decidedly summery.While there are splashes of fall colour here and there, and some trees have started to shed their foliage, plenty of others remain green.
Why, you ask?
The days are surely getting shorter, which is normally a signal for trees to shut down for the winter and drop their leaves.
But it's been a very warm fall. The average daily high temperature so far this October is 18.9 C — well above the normal of only 12.7 C. Basically, some trees have been "tricked" into staying green far past their normal time.
http://www.cbc.ca/news/canada/ottawa/why-are-trees-still-green-late-october-1.4373672