Israel’s Meteorological Service on Thursday published its first quantitative forecast for how a powerful El Nino developing in autumn 2026 could reshape the country’s weather, laying out three scenarios that range from a four-hour flash flood to a full Mediterranean hurricane. The service says all three carry severe potential impact, even if each remains a low-probability outcome in a winter where El Nino conditions are already present in the Pacific.
The report, the IMS’s first attempt to translate global El Nino signals into specific local threats, comes as the U.S. National Oceanic and Atmospheric Administration’s Climate Prediction Center confirmed that El Nino conditions have developed across the central and eastern equatorial Pacific. NOAA puts the chance of a very strong event during November through January at 63 percent, a level that would rank among the largest El Nino episodes since 1950.
A First Detailed Look at Israel’s El Nino Risk
The IMS report is structured unusually for a national weather service. Instead of a single seasonal outlook, it lays out three discrete extreme-weather scenarios, each tied to a specific forecast lead time, so emergency planners can match their preparations to the kind of event that materializes. The agency framed the work as a response to a climate it no longer trusts historical averages to describe.
“The Meteorological Service identifies an increase in the frequency and intensity of some extreme weather events, as well as the appearance of events that were previously considered unlikely in terms of their timing, location, or intensity in Israel,” the report said. It added that with “such irregular conditions in the atmosphere, relying on historical statistics alone may not be enough for preparedness needs.”
El Nino itself is a recurring Pacific Ocean phenomenon, a periodic warming of surface temperatures in the central and eastern equatorial band that disrupts the global jet stream. Its wider effects, per the IMS report, include wetter weather and coastal flooding in the U.S., severe drought and hotter-than-average temperatures in Australia, Indonesia and parts of Southeast Asia, disrupted monsoon rains in India, and higher temperatures alongside a wetter winter across the Mediterranean.
Three Scenarios, Ranked by Lead Time
The IMS split its worst-case thinking into three categories. Each scenario carries a different geographic footprint, a different peak intensity, and a different window in which forecasters believe they can flag the threat before it arrives. None of the three is being treated as a base case; the service’s job, in its own telling, is to make sure planners are not surprised whichever scenario breaks loose.
Scenario one is a short, intense rain event lasting up to four hours. Scenario two is prolonged rainfall lasting 24 to 48 hours. Scenario three is a Medicane, a Mediterranean cyclone with some hurricane-like characteristics, smaller and shorter-lived than a tropical hurricane but capable of comparable damage over a tighter footprint.
| Scenario | Duration | Peak hazards | Areas most exposed | Forecast lead time |
|---|---|---|---|---|
| Short intense rain | Up to four hours | Winds up to 150 km/h, hail 5-7cm, intense lightning | Coastal cities from Ashkelon to Nahariya | 3-5 days; sharper detail 24 hours before |
| Prolonged rainfall | 24 to 48 hours | 270 to 400mm rain, urban flooding, flash floods | Coastal plain, Shfela, central and northern mountains | 5-7 days; focused data 1-3 days before |
| Medicane | September to January window | Winds up to 120 km/h, hundreds of mm rain, turbulent seas | Central and southern coastal plain | Up to 5 days for development potential |
Forecast lead times matter because they decide which agencies can prepare. The shorter scenario can be flagged three to five days in advance, with sharper spatial detail about a day before impact. The longer scenarios earn five to seven days of warning, enough for utilities, military airfields, and municipalities along the coastal plain to position crews and stage equipment.
How Big This El Nino Could Get
The size of the underlying Pacific signal is what makes the IMS scenario exercise worth doing. The service’s modeling points to a Pacific temperature anomaly of about 3.7 to 3.8 degrees Celsius during the autumn peak, per a parallel write-up of the IMS quantitative analysis, against a previous record of about 2.6 degrees set during the strong 2015 event.
NOAA’s latest weekly Nino-3.4 index, the standard Pacific thermometer for El Nino, sits at +0.7 degrees Celsius, with the easternmost Nino-1+2 index at +2.1 degrees. The agency expects conditions to strengthen into Northern Hemisphere winter 2026-27, and ties the high confidence to anomalously high oceanic heat content and expanding westerly wind anomalies across the equatorial Pacific.
Where the Worst Weather Would Land
The first scenario is the one the IMS draws most sharply. Under the short, intense rain case, coastal cities take the worst of it, with wind gusts of up to 150 kilometers per hour, hailstones five to seven centimeters in diameter, and intense lightning storms, with damage likely to transportation infrastructure, energy, and agriculture. The service names the cities most exposed, drawn from the full coastal strip:
- Southern coast: Ashkelon and Ashdod
- Central coast: Rishon LeZion, Tel Aviv, and Netanya
- Northern coast: Haifa and Nahariya
The window for that scenario runs from September through January 2027, which is also when Medicanes become plausible. The prolonged rainfall scenario, by contrast, is most likely between November and January, and threatens the coastal plain, the Shfela lowland area, and the central and northern mountain ranges, with serious urban flooding, flash floods in river basins, road closures, and risks to critical facilities, including military airfields.
The Medicane scenario would be felt most along the central and southern coastal plain, where dangerous urban and flash flooding would arrive as stream and river levels rise, and severe damage would hit energy and transportation infrastructure. The third-scenario Mediterranean cyclones can drop hundreds of millimeters of rain, bring winds of up to 120 kilometers per hour, and whip up turbulent seas.
How Much More Rain Israel Could See
Beyond the three disaster scenarios, the IMS has tried to put a normal-case number on what an extreme El Nino year means for Israeli rainfall. The service’s model suggests that each one-degree rise in the El Nino index could add about 11 to 15 percent to Israel’s annual rainfall, depending on the region, a relationship that has practical implications once the temperature anomaly crosses the two-degree mark.
Some regions would see a larger share of that surplus. In the Judean Mountains and the northern Negev, rainfall could reach 140 to 145 percent of the multiyear average. In the Golan Heights and eastern Galilee, the IMS identifies a possible rise to about 136 to 137 percent of the multiyear average. The numbers come from a parallel IMS quantitative analysis that the agency released alongside the three-scenario document.
The IMS also flagged a possible rise in the probability of significant snow accumulation in the mountains and in the number of snowy days, after three to four winters without a meaningful snow event in the northern and central mountains. The report frames the 2026/27 season as carrying “great potential for a rainy, event-heavy winter that includes extreme events and perhaps even snow events.”
What the Forecasters Can and Cannot Promise
The IMS is careful to draw a line between scenarios and certainties. Head of service Dr. Amir Givati stressed that although the models point to a higher probability of a wetter-than-average winter under extreme El Nino conditions, uncertainty remains high, and even strong El Nino years are not always accompanied by unusual winters in Israel because of the influence of other climate factors.
The agency spelled out that tension on the page. “The positive but statistically insignificant tendency toward extreme events in El Nino winters indicates that there is greater potential for extreme events in El Nino years,” the report said, going on to note that the potential is sometimes realized and sometimes not. “Sometimes this potential is realized in other parts of the world, while barometric highs remain over Israel, blocking the arrival of troughs and lows and preventing it from materializing.”
That is why the report leans on preparedness scenarios rather than a single number. With the next NOAA ENSO diagnostic discussion scheduled for July 9, forecasters on both sides of the Atlantic will get another data point before the autumn peak arrives. For Israeli planners, the IMS message is that historical averages are no longer the right tool, and three concrete threat profiles, even if unlikely, are the better preparation.
Why This Year Stands Apart
What makes the 2026/27 outlook unusual is the combination of two things, a Pacific signal that may surpass the 2015 record, and an Israeli forecast infrastructure that, for the first time, has quantified how that signal translates into specific local hazards. NOAA’s 63 percent probability of a very strong event is the agency’s own framing of the upside risk; the IMS scenarios are the matching local translation.
Both agencies, in their own ways, are saying the same thing: the next several months are not a base-case forecast but a stress test. The probability of any one of the three scenarios is low. The cost of being unprepared for the worst of them, with cities from Ashkelon to Nahariya in the blast zone, is what the IMS is asking emergency planners to plan against.
Frequently Asked Questions
What is El Nino and why does it matter for Israel?
El Nino is a recurring climate phenomenon in which surface temperatures in the central and eastern equatorial Pacific Ocean warm up, disrupting the global jet stream. The IMS says its effects include wetter weather and coastal flooding in the U.S., severe drought and hotter-than-average temperatures in Australia, Indonesia, and parts of Southeast Asia, disrupted monsoon rains in India, and higher temperatures with a wetter winter across the Mediterranean.
How strong could the 2026 El Nino be?
NOAA puts the chance of a very strong El Nino during November through January at 63 percent, which would rank among the largest El Nino events in the historical record going back to 1950. The IMS’s own modeling points to a Pacific temperature anomaly of about 3.7 to 3.8 degrees Celsius during the autumn peak, against a previous record of about 2.6 degrees during the 2015 event.
What are the three scenarios the Israel Meteorological Service laid out?
The IMS released three scenarios: short intense rain lasting up to four hours with winds up to 150 km/h and hail 5-7cm in diameter; prolonged rainfall lasting 24 to 48 hours dropping 270 to 400mm; and a Medicane, a Mediterranean cyclone with some hurricane-like characteristics, bringing winds up to 120 km/h and turbulent seas.
Which Israeli cities are most at risk?
The IMS names coastal cities from south to north as the most exposed to the short intense rain scenario: Ashkelon and Ashdod in the south, Rishon LeZion, Tel Aviv, and Netanya in the center, and Haifa and Nahariya in the north. The prolonged rainfall scenario threatens the coastal plain, the Shfela lowland area, and the central and northern mountain ranges.
When could the worst weather hit?
The first scenario could hit any time between September and January 2027. The prolonged rainfall scenario is most likely between November and January. The Medicane scenario also falls between September and January. The next NOAA ENSO diagnostic discussion is scheduled for July 9, 2026.
