The 2015-16 El Nino event was a major phenomenon, affecting weather worldwide. It is one swing of the slow pendulum called the El Nino Southern Oscillation (ENSO).
This is a natural system whereby warm water in the equatorial Pacific appears to slosh from west to east and back again.
The other side of the pendulum swing is called La Nina, the female child, in Spanish. Just as a boy is opposite to a girl, so La Nina produces many opposite weather effects to El Nino.
We can expect this La Nina to last, with approximately 75 percent probability, until at least April 2018.
This brings with it a strong upwelling of cold, nutrient-rich water along the Peruvian coast, boosting the fish catch.
It was the periodic failure of this industry which first alerted us to the alternative swings of El Nino (fishing collapse) and La Nina (abundant catch).
Most importantly, moving warm water from one side of the Pacific to the other moves the weather patterns of the whole world. Major areas of uplift are transposed to the west, taking the heaviest rain with them.
The effects elsewhere in the world of the current La Nina will be notably dramatic:
Over the next four months, it is likely to be:
much wetter than normal in: much drier than normal in:
Northern Australia US Gulf coast
It may well be colder, yet drier than normal in Alaska and western Canada, with this cold often penetrating into the northern Great Plains and the western US.
There will be other variations in the weather that might otherwise be expected, during this northern winter, some of which may be caused by La Nina. However, it is only one influence on the atmosphere.
A warming world produces equally dramatic changes – the loss of complete ice cover of the Arctic Ocean, in winter, is likely to be more of an influence than La Nina during in Europe this winter.
For further reading: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml