El Niño conditions in the equatorial Pacific started emerging during the Northern Hemisphere spring of 2023 and developed rapidly during summer, reaching a level consistent with a moderate El Niño by September 2023. The latest forecasts from the WMO Global Producing Centres for Long-Range Forecasts indicate a high probability (90%) of El Niño continuing throughout the upcoming Northern Hemisphere winter, with conditions at the peak of the event corresponding to a strong El Niño. Chances of a transition to ENSO-neutral are very low (10%). Drawing on evidence from historical warm Tropical Pacific episodes of similar proportions, it is anticipated that this event will have substantial and widespread effects on weather patterns through much of the tropics and beyond at least until end of 2023 and first quarter of 2024. This disruption is likely to have significant impacts on communities, economic activity or natural ecosystems in some regions. In the coming months, National Meteorological and Hydrological Services (NMHSs) will closely monitor any change in the status of ENSO and promptly provide revised assessments, as necessary.