The weather in Spain could experience major changes during the next few weeks due to a phenomenon that is developing about 30 kilometers above the Arctic. International meteorological models are monitoring the possibility of a sudden stratospheric warming, an episode capable of weakening the polar vortex and altering the trajectory of storms and cold air masses that circulate through the northern hemisphere.
Meteorologists' attention is focused on the first days of November 2026, when forecasts point to a disturbance of an unusual intensity for this time of year. The Climate Prediction Center of the United States (NOAA) has warned of the possibility that the polar vortex will undergo an alteration during the coming week, with potential consequences for the atmospheric circulation of the following months.
Spain could be affected by a change in the distribution of rainfall, the arrival of cold air, or a greater succession of Atlantic storms, although it is still not possible to determine which scenario will ultimately prevail. In fact, a warming of the stratosphere does not necessarily mean that temperatures will increase at the surface, nor does it guarantee a cold wave.
What sudden stratospheric warming is and why it occurs
Sudden stratospheric warming (SSW) is an atmospheric phenomenon characterized by a very rapid rise in temperatures in the stratosphere, the layer located approximately between 10 and 50 kilometers above.
According to the State Meteorological Agency (AEMET), during these episodes the temperature of the polar stratosphere can rise more than 25 degrees in less than a week. In the most intense cases, the increase can exceed 50 degrees in just a few days.
The phenomenon is related to the propagation of large atmospheric waves from the troposphere, where the weather we experience daily develops, toward the stratosphere.
When these disturbances reach the upper layers, they can alter the winds that surround the North Pole. The result is a weakening of the stratospheric polar vortex, which can shift, deform, or even split.
In the episodes of greatest intensity, the winds that normally flow from west to east come to reverse their direction. This change is one of the criteria used by meteorologists to identify a major sudden stratospheric warming.
What the polar vortex is and what happens when it weakens
The stratospheric polar vortex is a large circulation of winds that surrounds the Arctic during the cold months. It forms each autumn and usually reaches its greatest intensity during winter, when the absence of solar radiation favors extremely low temperatures over the pole.
Under normal conditions, the strong winds that surround this region help maintain a relatively organized circulation. However, when the vortex weakens, the distribution of air masses and atmospheric currents can change considerably.
This alteration can be transmitted to lower layers of the atmosphere and influence the polar jet stream, a band of intense winds that plays a role in the movement of storms and anticyclones.
When the jet stream shows more pronounced undulations, anticyclonic blockages can form at high latitudes. These situations favor certain masses of cold air advancing toward more southern regions and storms taking different paths than usual.
The important point is that the warming occurs at great height, but its consequences can manifest as episodes of cold at the surface. This is not a contradiction, but two related atmospheric processes that occur at different altitudes.
Models are monitoring an exceptional episode at the beginning of November
Current forecasts have aroused special interest because a major sudden stratospheric warming during the first half of November would be extraordinarily early.
The meteorological monitoring service Polar Vortex Earth, which analyzes the forecasts of the European Centre for Medium-Range Weather Forecasts (ECMWF), indicated this Sunday, November 1, that the 50 scenarios of its prediction ensemble contemplated a reversal of the vortex winds before November 15.
This coincidence among the scenarios is a notable signal, although it does not constitute confirmation that the phenomenon will occur. The models can modify their results as new observations are incorporated.
According to the historical records used by this system, no major sudden stratospheric warming has been documented before November 28 since 1959. Therefore, a reversal of the winds over the next few days would constitute a very unusual episode.
Meteorologists also observe a deformation of the polar vortex, which could take on a very elongated structure before shifting or temporarily splitting.
Climatologist Judah Cohen, specialized in the behavior of the polar vortex, has noted that important uncertainties still exist about the consequences of such an early episode. Although the models anticipate a considerable disturbance, its influence on the weather in Europe will depend on how atmospheric circulation evolves over the coming weeks.
How the stratospheric warming could affect Spain
One of the possible consequences for Spain would be an increase in Atlantic storm activity, especially if the weakening of the vortex favors the appearance of persistent high pressures in the northern latitudes of the Atlantic.
In certain circumstances, these blocking patterns force the storms to circulate farther south than usual, which can increase the arrival of fronts to the Iberian Peninsula.
AEMET has documented that some important stratospheric warmings are related to a negative phase of the North Atlantic Oscillation (NAO), a pattern that, in certain configurations, can favor precipitation in the basins of the large Atlantic rivers.
Galicia, Castilla y León, Extremadura and western Andalusia could register a greater frequency of rainy episodes if that circulation were established, although there is still no sufficiently precise forecast to anticipate specific rains in these communities as a consequence of the possible warming.
Another possibility is that the changes in circulation favor cold-air incursions from the north or east of Europe, with drops in temperature and snowfall in mountain areas.
However, there is also a third scenario: that the stratospheric disturbance does not significantly alter the weather over Spain or that the country remains under the influence of high pressures and relatively stable conditions.
Therefore, it is not correct to state that the sudden stratospheric warming will necessarily cause a cold wave or a period of heavy rain in Spain.
When its effects could be noticed: from mid-November to December
Although the models place the possible disturbance of the polar vortex in the first days of November, its consequences on surface weather could take several weeks to appear.
The British meteorological office, Met Office, explains that the effects of these episodes usually become evident after the disturbances in the stratosphere spread to the troposphere.
The process can last for two, three or more weeks, depending on the intensity of the warming and the evolution of atmospheric currents.
In the current scenario, this means that the possible changes in Spain could begin to be noticed during the second half of November or already in December, provided that the disturbance comes to influence the lower layers.
In addition, not all stratospheric warmings produce significant consequences. Research funded by the European Union through the stratoIMPACT project indicates that approximately two-thirds of these episodes do end up affecting the weather, while in other cases their influence on the surface is limited.
The evolution over the next few weeks will be decisive in determining whether the episode ends up modifying the behavior of European storms.
What the AEMET says about temperatures and rainfall in Spain
Despite the possible weakening of the polar vortex, AEMET's seasonal forecast does not currently point to a particularly cold quarter in Spain.
For the period between November 2026 and January 2027, the meteorological agency indicates a very high probability that average temperatures will be above usual values throughout the country.
As for precipitation, the forecast indicates a high probability of rainfall above normal on the Atlantic side, especially in the northwest of the peninsula. For the rest of the territory, the models do not show a sufficiently clear signal to highlight a wetter or drier scenario.
These forecasts refer to the average behavior over three months, so they do not rule out isolated episodes of intense cold, snowfall, or heavy precipitation. A quarter may end up being warmer than normal and, at the same time, record several days with especially low temperatures.
The seasonal forecast also does not allow the forecasted rains to be directly attributed to stratospheric warming, since numerous atmospheric and oceanic factors come into play.
The precedents of 2018 and 2021: cold and rain after disruptions of the polar vortex
Meteorologists have precedents that make it possible to study the possible consequences of this phenomenon.
In February 2018, an important sudden stratospheric warming occurred that was related to changes in European atmospheric circulation. During the following weeks, a strong influx of cold air affected numerous regions of the continent, in an episode known as the "Beast from the East".
In Spain, that alteration helped establish a pattern favorable to Atlantic precipitation. AEMET has studied how the episode was associated with a circulation that favored the arrival of storms to the Peninsula.
Another notable case was recorded in January 2021, coinciding with a period of important atmospheric anomalies during which Spain suffered the storm Filomena and a subsequent cold wave.
However, the temporal coincidence between a stratospheric warming and a storm does not by itself show that the former caused all the observed phenomena. The effects depend on the position of the anticyclones, the path of the storms, and other factors that act on the atmosphere.
Does this mean that Spain will have a colder winter?
Not necessarily. A sudden stratospheric warming may increase the chances of certain weather patterns, but it does not by itself determine what the entire winter will be like.
In fact, the consequences can be very different among nearby countries. While one part of the European continent records exceptionally low temperatures, other regions may experience a mild and rainy environment.
The main unknown for Spain is where the anticyclonic blocks will be located and what path the polar jet stream will take if the forecast alteration finally occurs.
Meteorologists will especially follow the evolution of the stratospheric winds during the first days of November and will later check whether the changes are transmitted to the lower layers of the atmosphere.
For now, the most rigorous scenario is to keep several possibilities open: more storms, occasional episodes of cold, or even a limited influence on Spain. The official forecast of the AEMET continues to point to a quarter warmer than usual and with a greater probability of rain on the Atlantic side.
The sudden stratospheric warming could modify this panorama at specific moments, but it is still too early to announce a widespread cold wave, extraordinary snowfalls, or a definitive change in the trend of the weather in Spain.