This is worth reading, as a primer on weather and climate prediction.

http://fivethirtyeight.com/features/why-we-dont-know-if-it-will-be-sunny-next-month-but-we-know-itll-be-hot-all-year/

Weather forecasts more than a week ahead are notoriously unreliable. Yet climate scientists have been predicting since December that 2016 will be the warmest year since at least the 19th century. What gives?