Every time we write about El Niño the comments are filled with surfers wanting to know the knock-on effects outside their region. While there are many areas affected these effects will often be considerably more subtle than those in the North Pacific so here's some raw data for you to use for your own analysis.
These charts are simply graphing the AVERAGE surface wave height (of all swells combined) for December from the years in question. Possibly we could consider a broader window in winter as useful and we'll look to create charts for every year shortly. But at a glance you can see the clear difference between last year and the El Niño winters of 2009 and 1997. Particularly the crazy year of 1997, the most extreme on record.
Dec 1997 - Strong El Niño
Temperature Difference +3.57°C
Dec 2009 - Moderate El Niño
Temperature Difference +1.26@deg;C
Dec 2010 - Moderate La Niña
Temperature Difference -1.58@deg;C
Temperature Difference +0.91@deg;C
We're currently looking at a temperature difference of +2.34 in the same region and the effects on the North Pacific should be consistent with this. However in other regions you can see why we're more reluctant to make sweeping statements. For example in the North Atlantic you can see that the difference between 1997's extreme El Niño and 2010's weak La Niña is considerably less than the variance between last winter and either of these. In these other regions it may be possible to discern an effect, but it doesn't mean it'll be the dominant one by a long stretch - there are many other climate cycles to consider.
The cover image at the top of the page is just a playful attempt to visualise the difference between these last two El Niño years, and last year, using Photoshop's blending modes - but even here you can see that the variation in the North Atlantic is larger than the variation in the North Pacific - despite a lack of such strong link to El Niño. We can be 100% confident that this winter won't look exactly like last winter, or any that proceeded it, and not all this variation will be a result of El Niño.
* Temperature difference data taken from the NINO 3 region in November of each year