While El Niño forms across the tropical Pacific, forecasters look at one region in particular, called Niño3.4, to monitor a three-month average of sea surface temperatures compared to the long-term average.
A strong El Niño or ‘super El Niño’ is when temperatures rise above 1.5C.
Forecasts from the European Center for Medium-Range Weather Forecasts (ECMWF), NOAA and BoM are all largely consistent.
ECMWF’s latest forecasts show that more than half of the forecast models predict temperatures will rise by more than 2.5C by autumn.
Johnson said anything on this issue would be a “historically powerful event.”
BoM forecasts also confidently indicate the possibility of a very strong El Niño later this year.
Some forecast data suggest temperature rises could exceed 3C, beyond the current high of 2.7C recorded in 1877.
It is important to note that this was a very different era with limited observations, so much uncertainty remains in the reported temperatures.
El Niño lasted for about 18 months, triggering a deadly global climate phenomenon that caused severe droughts and widespread famine across Asia, Brazil and Africa, killing millions and causing severe flooding in other regions such as Peru.
The last ‘very strong’ El Niño occurred in 2015-2016, when the average three-month (November, December and January) Niño3.4 temperature rise reached 2.4C.
