The further south you are, the warmer the ocean will be. No question this, most powerful ever, EN will impact Mexico and every other country south to the equator and beyond. Lots of good info out there about specific, local impacts for this half of the planet. Ya gotta love Google. Expect weather extremes and hope to be disappointed.
While typically EN's impact is most often felt during the winter this year's event has been active for several months already and last time I checked my calendar winter was still 2 weeks+ down the road. California, just to name one area in the crosshairs, will likely have far more problems from too much water/precipitation and the resultant flooding, mudslides etc. than the drought.
Hang on to your socks folks, it is going to be a wild winter!
:E