Predict Denver's First Measurable Snowfall, 2023 | Contest ends midnight October 10th | ENTER HERE! La Niña November La Niña update and winter outlook Historically, if La Niña is going to strengthen, this is the time of year it will happen. So, let’s see what it's up to. The graphic above shows how La Niña has been behaving since the middle of August. To be classified a La Niña, that dotted blue line needs to be at or below -0.5 for three consecutive months.