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El Niño

El Niño is a term for the warming phase of the El Niño Southern Oscillation (ENSO), a cyclical weather pattern that influences temperature and rainfall across the global. It is a warming of the central to eastern tropical Pacific Ocean. During an El Niño event, sea surface temperatures across the Pacific can warm by 1–3°F or more for anything between a few months to two years. El Niño impacts weather systems around the globe, triggering predictable disruptions in temperature, rainfall and winds.

Forecast for 2017

The latest global ENSO update issued by the World Meteorological Organization on 28 April indicates a 50%-60% probability of an El Niño episode during the second half of 2017, although some national meteorological centers put the probability slightly lower.

While the most accurate seasonal forecasts will not be available until late June, the possibility of a 2017 El Niño raises significant concerns. Even if an El Niño episode does not fully develop in 2017, sea surface temperatures and other large-scale climatic patterns may already be in motion that could produce negative impacts in vulnerable countries.

El Niño usually peaks in intensity between October and January, however its impacts on weather patterns (rainfall, storms) and consequent humanitarian impacts on food security, health, access to water and sanitation, livelihoods and agriculture production can happen both before and after the peak period.

It is critical that at-risk states and their international partners heed the early warning signs and begin risk mitigation activities.

High-risk countries for the period June-September

As part of a set of global inter-agency Standard Operating Procedures under development to improve the response to early warnings of ENSO episodes by the United Nations and its partners, an inter-agency analysis group was co-convened by OCHA, FAO, and WFP under the auspices of the IASC to analyse the current forecasts together with information on vulnerability, coping capacity and residual impacts from the 2015/2016 ENSO in order to identify the countries at highest risk over the period June-September 2017. The cell came up with a list of 19 high-risk countries:

Cambodia (below-average rainfall)
Lao DPR (below-average rainfall)
Marshall Islands (above-average rainfall)
Myanmar (below-average rainfall)
Pakistan (below-average rainfall)
Papua New Guinea (coastal areas are expecting below-average rains and highlands are forecast to receive above-average rains)
Timor-Leste (below-average rainfall)
Vanuatu (below-average rainfall)
Vietnam (below-average rainfall)


Central America, the Caribbean and South America
El Salvador (below-average rainfall)
Guatemala (below-average rainfall)
Haiti (below-average rainfall)
Honduras (below-average rainfall)
Nicaragua (below-average rainfall)
Venezuela (below-average rainfall)


Ethiopia (below-average rainfall)
Eritrea (below-average rainfall)
South Sudan (below-average rainfall)
Sudan (below-average rainfall)


The analysis is neither fixed nor final. Both the global El Niño outlook and the specific weather forecasts will continue to evolve and may well improve. The global ENSO analysis cell will update the attached analysis on a regular basis as long as a significant chance of an El Niño episode remains.