>90%
very strong category
Northern Hemisphere autumn and winter 2026-2027
NOAA CPCThe question behind the headline
Will Romania get cold? The polar vortex is only part of the answer.
El Niño is strengthening in the Pacific. For that signal to become a cold week in Romania, it must connect with the stratosphere, the polar jet and a regional pattern close to the event.
The polar vortex circulates high in the stratosphere. The polar jet sits closer to the weather we feel. This page follows how upper-air circulation can shape surface weather.
In briefNOAA is describing the odds for El Niño in the Pacific. For Romania, the answer depends on the jet configuration and forecasts closer to the event.
Why nowStarting point: Romanian media coverage of a possible Super El Niño and its effects on Romania.
The short answer
The number describes the Pacific. A Romania forecast comes later.
The question and the evidence change between those two points. Follow the same transition in four steps.
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El Niño raises ocean temperatures
Equatorial Pacific surface waters are warmer than average. NOAA estimates a greater than 90% chance of a very strong episode during Northern Hemisphere autumn and winter.
NOAA CPC -
Upper-air circulation can be disturbed
Atmospheric waves can change the vortex above the North Pole. Historical data show a link between ENSO and sudden stratospheric warmings, and that relationship changes between winters.
Butler et al. 2011 -
The jet changes which region is affected
After a major stratospheric event, surface effects vary by place and time. NOAA maps show regional averages, not the temperature of one country.
NOAA Climate.gov -
The local forecast arrives close to the event
A week of frost or snow requires a specific pattern in the jet, the Atlantic and pressure fields. The useful answer comes from updated regional forecasts.
regional data
One diagram
What changes when the vortex weakens
The slider shows two simplified configurations. Follow the same scene: the vortex above, the jet in the middle and cold air that can move south in some regions.
Choose a state with the arrow keys or the slider.
Stable vortexDisturbed vortex
0
A more stable vortex
Stratospheric winds remain stronger and more circular. Cold air is more contained in the Arctic, while the jet tends to stay farther north.
1
A weakened or disturbed vortex
Stratospheric warming or a shift in the vortex can make the jet more wavy. Arctic air can move south in some regions.
Explanatory diagram. It is not a forecast or a live measurement.
The diagram shows a more stable vortex.
What we know now
NOAA estimates the chance of a strong El Niño
On 13 August 2026, NOAA estimated a greater than 90% chance of the "very strong" category during Northern Hemisphere autumn and winter. For October-December, the chance of a historic event was 69%, at a RONI threshold of at least +2.5°C.
69%
historic event
October-December 2026, RONI at least +2.5°C
NOAA CPCWhat these percentages cannot tell you
Both percentages refer to El Niño in the Pacific. They do not give a temperature for Europe on their own. That requires the stratosphere, the polar jet and regional forecasts.
A 2021 test
In 2021, tropospheric circulation mattered more at the surface
After the major sudden stratospheric warming in 2021, one study found limited surface impacts in North America. Tropospheric circulation mattered more for the cold that was observed.
Read the Nature Communications studyThe Romania question
For one specific week
What should you watch next?
For one specific week, three things matter more than the El Niño headline.
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The stratosphere
Is there a major sudden stratospheric warming or a displaced vortex?
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The polar jet
Is it bending south over Europe?
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The local forecast
What do the models show for Romania in the near-term window?
A seasonal signal tells you where to look. A local forecast answers for one specific week.
How the claims are separated
Sources you can check
NOAA is the source for the percentages and the vortex explanation. Research tests the relationship between ENSO and the stratosphere. The Libertatea article is the starting point for the public question.
The number, the mechanism and the forecast do different jobs
The number comes from the NOAA bulletin. The mechanism comes from NOAA Climate.gov and research. A Romania forecast stays tied to regional evidence close to the event.
NUMBERa probability for El Niño with a window and threshold
MECHANISMa documented relationship between atmospheric layers
FORECASTa regional estimate for a specific time window
forecast
NOAA CPC
ENSO Diagnostic Discussion, 13 August 2026
The discussion estimates a greater than 90% chance of a very strong El Niño during the Northern Hemisphere autumn and winter of 2026–2027. For October–December 2026, the chance of a historic event is 69% at a RONI threshold of at least +2.5°C. NOAA says El Niño-consistent impacts become more likely without becoming guaranteed.
forecast
NOAA CPC
Long-Lead Seasonal Outlook, 16 July 2026
The 16 July seasonal outlook gave an 81% chance of a very strong El Niño in OND 2026. The 13 August diagnostic uses an update and two different thresholds. The product remains U.S.-focused and does not provide a Romania forecast on its own.
institutional explainer
NOAA Climate.gov
Understanding the Arctic polar vortex
It describes the polar vortex as stratospheric circulation and separates it from the tropospheric polar jet, which sits closer to day-to-day surface weather.
institutional explainer
NOAA Climate.gov
But what does a polar vortex breakdown look like down here?
It shows that surface cold signals after major sudden stratospheric warmings vary by region and time. NOAA's maps average 42 observed events between 1958 and 2023, around 30 days after each event; they describe patterns, not local forecasts.
research
Butler et al.
El Niño, La Niña, and stratospheric sudden warmings: a reevaluation
The 53-year reanalysis finds a statistical relationship between ENSO and sudden stratospheric warmings, with higher frequency in ENSO winters. The relationship does not become a required sequence for every El Niño event.
research
Nature Communications
Limited surface impacts of the January 2021 sudden stratospheric warming
The study finds limited surface impacts from the 2021 stratospheric warming in North America; tropospheric circulation mattered more for the cold that was observed.
media context
Libertatea
Super El Niño and its possible influence on Romania in 2026-2027
The article is the public-media starting point for the question. It is used here as context, not as the source for meteorological figures or mechanisms.
Checked 16 August 2026. Revisit when NOAA issues a new ENSO discussion, a major sudden stratospheric warming occurs, or forecasts for Europe and Romania change the relevant evidence.