Observing the historical behavior of bitcoin in recent years, it is easy to see that the months of December are usually quite volatile and disruptive, so they tend to be determinants to configure the trend that will continue during the following months, however, it is easy to observe that there have been end-years with bearish, bullish and stable trends alike, so I still do not understand why many assume that December is always a good year for bitcoin.
I prefer to be quite cautious in my forecasts for December, because I do not see conditions to expect a significant jump in the price of bitcoin since many investors seem to have been disillusioned by the performance of the market this year, and things seem to have returned to a normality that until before 2017 seemed to prevail in the market.