Currently, the “departure from average” is being computed relative to 1986-2015 seasonal averages. Eventually, because of rolling the climatology forward in time, the current numbers will change when the climatology for period 1991-2020 is used. When does this change come into effect ? Currently, ONI index are OND2019 +0.5 C, NDJ2020 +0.5 C, DJF2020 +0.5 C, JFM2020 +0.5 C Would a weak El Nino be declared if FMA2020 is +0.5 C or higher ? It would satisfy the NOAA criteria for El Nino !