Planning for fall but considering winter. Thank you!
It all depends on what you consider to be very cold :) For example, in December it's around 0 - 2 degrees (around 36 Fahrenheit), which I personally don't think it is very cold, but it rains a lot during that time and due to the high level of humidity, it feels colder than it really is. I would recommend going in September if you can, it's beautiful there and the weather is comfortable. In October it already starts raining.
Hope it helps.
In November there're a lot of rainy days, but the coldest month is January -
38° - 30°F