There are increasing evidence that we'll have our first El Niño since 2010 sometime within the next year. Just for fun, I thought it would be interesting to try to predict what the annual global average temperature would be if an El Niño developed as expected.
I took Berkeley Earth land + ocean annual temperature data starting in 1970 and categorized each year as El Niño, La Niña, or neutral using average MEI data for each year. Any year with an MEI average ≥ +0.5 was classed as an El Niño year. La Niña years had MEI values ≤ -0.5, whereas neutral years were between -0.5 and +0.5. I then performed a separate linear regression on each category.