Trees in the Netherlands are dropping their leaves some two to three weeks later than they did 60 years ago because of the warmer weather in September and October, according to website Nature Today.

The average temperate in both months was around 15°, some three degrees warmer than 50 years ago, the website said. Nor has there yet been any frost.

“Trees lose their leaves for two reasons,” biologist Arnold van Vliet told news website Nu.nl. “Both shorter days and lower temperatures show a tree that it is winter.”

Trees are also more vulnerable to autumn storms if they have not shed their leaves and are more likely to blow over in strong winds.