Tag: northern and central Europe

Sudden stratospheric warmings (SSWs), temporary breakdowns of the winter stratospheric polar vortex, raise the odds of extreme cold and resulting spikes in electricity demand across northern and central Europe by 1.5- 3 times, according to a University of Exeter- led study.

Normally, strong, stable westerly winds form the stratospheric polar vortex high above the Arctic in winter.

Roughly once every two years this vortex temporarily breaks down in an SSW. The stratosphere warms, but cold surface air can spill southward into Europe (and North America). Cold weather after an SSW, such as the 2018 “Beast from the East”, typically arrives a few weeks later, giving energy providers and governments a useful early- warning window.

Key findings

• Extreme electricity demand was defined as at least 20% above average and is driven mainly by heating needs.
• Impacts vary by country: Scandinavian nations (better adapted to cold) show smaller demand increases, while France (with a highly electrified system) sees a steeper rise.
• The UK is currently relatively well buffered by gas central heating, but the shift toward electrification (e.g., heat pumps) under net- zero goals will make cold, low- wind periods more challenging for grid reliability and costs.

Lead author Dr Regan Mudhar (now at the University of Lausanne) noted the clear statistical link between SSWs and extreme demand events, using the 2018 polar- vortex split as a prominent example.

Co- author Dr Hannah Bloomfield (Newcastle University) highlighted the growing relevance for energy systems as heating electrifies. Mudhar also observed that while greenhouse- gas- driven warming continues, SSWs are still expected to occur and bring cold snaps, so preparedness matters alongside emissions reductions during the renewable transition.

The peer- reviewed paper, “The influence of sudden stratospheric warmings on extreme European electricity demand,” appears in Meteorological Applications (DOI: 10.1002/met.70241) and was funded by the Natural Environment Research Council GW4 and Doctoral Training Partnership. The work builds on earlier research linking stratospheric variability to European weather and energy impacts.

Sudden Stratospheric Warmings (SSWs) mainly affect the Northern Hemisphere in winter. Their surface impacts (cold air outbreaks, shifts in the jet stream, storm tracks, etc.) vary a lot by location:

• Northern and Central Europe (the focus of the recent University of Exeter study): Higher chance of extreme cold and elevated electricity demand (especially heating- driven) in the weeks after an SSW.
• North America (especially eastern US and Canada): Can also bring cold outbreaks, though the exact patterns differ from Europe.
• East Asia: Sometimes linked to colder conditions.
• Southern Hemisphere, tropics and high Arctic: Impacts are generally weaker, different, or minimal for the classic “SSW → cold snap” pathway discussed in the European energy study.

In Europe, Sudden Stratospheric Warmings (SSWs) most commonly increase the risk of colder-than- average winter weather, especially in northern and central regions, with knock -on effects for energy demand.

Typical weather impacts

SSWs disrupt the stratospheric polar vortex and often lead (within days to a few weeks) to a more negative phase of the North Atlantic Oscillation (NAO). This favours:

• High pressure over Scandinavia or the North Atlantic (“blocking”).
• A southward shift or weakening of the jet stream.
• Easterly or northerly winds that draw cold continental or Arctic air into Europe.

Key regional patterns (based on observations and studies):

• Northern and central Europe (Scandinavia, UK, Baltics, much of Germany, Poland, etc.): Higher chance of prolonged cold spells, more intense cold extremes (coldest days and nights often 2°C+ colder in SSW winters for parts of Scandinavia), and increased snow risk (especially in milder western areas like the UK and Ireland). Average winter temperatures can be ≥1°C cooler in SSW winters over large parts of Scandinavia.⁠
• Southern Europe: Tendency toward milder, wetter, and sometimes stormier conditions, with increased precipitation and more wet days.⁠
• Impacts are not guaranteed, only a portion of SSWs produce strong surface cold (roughly half or somewhat more, depending on the metric and region). Effects can persist for weeks to ~40- 60 and more days and vary by SSW type (more “radical” events tend to produce stronger, more widespread cold).

Classic example: the February 2018 SSW, which contributed to the “Beast from the East” cold outbreak across the UK and northern Europe.

Energy and societal impacts

The recent University of Exeter- led study (published in Meteorological Applications) specifically quantified electricity demand effects:

• SSWs raise the probability of extreme electricity demand (≥20% above average) in northern and central Europe by 1.5- 3 times. This is driven mainly by heating needs during cold weather.
• Demand response varies by country: Scandinavian nations (already well adapted to cold) show smaller relative increases; France (highly electrified heating) shows steeper rises. The UK is currently buffered by gas heating but faces growing challenges as heating electrifies (e.g., heat pumps) under net- zero goals.⁠

Related studies (e.g., for Finland) also link SSW winters, especially when combined with the easterly phase of the Quasi- Biennial Oscillation, to colder temperatures, lower wind speeds, higher electricity consumption, and reduced wind power generation.

Broader effects can include transport disruptions from snow/ice, higher cold- related health risks, and stress on energy systems (particularly as renewables and electrification expand). Storm- related hazards in northern Europe are often less frequent after SSWs than after strong- vortex periods.

Practical note

Because the surface response typically lags the stratospheric change by days to weeks, an observed SSW can serve as an early- warning signal for energy providers and governments to prepare for potential demand spikes. Not every event produces extreme cold, but the elevated risk is clear and statistically robust for northern and central Europe.

The Influence of Sudden Stratospheric Warmings on Extreme European Electricity Demand

Abstract and Core Findings

Sudden stratospheric warmings (SSWs) offer surface predictability up to several weeks ahead. They typically precede colder weather (including extremes) across the northern mid-latitudes. Because cold weather drives higher heating- related electricity demand, the authors investigate the SSW, demand link using:

• ERA5 reanalysis data and a weather- driven electricity demand model for various European countries.
• Subseasonal forecast experiments from the Stratospheric Nudging and Predictable Surface Impacts (SNAPSI) project, focused on the February 2018 SSW.

Key results:

• Extreme electricity demand (~120% of climatology, i.e., at least ~20% above average) is 1.5- 3 times more likely in the periods following SSWs across northern and central Europe.
• For the specific February 2018 SSW (which preceded a notable European cold outbreak), the SNAPSI nudged experiments show a robust simulated increase in extreme demand risk that can be attributed to the SSW itself.
• This creates a practical “window of opportunity” for earlier prediction of extreme European electricity demand risks after SSWs are observed.

Methods Overview

• Historical analysis: Identified 30 major SSWs (1979/80- 2024/25) using the Charlton & Polvani criterion on ERA5 10 hPa, 60°N zonal wind. Examined temperature-derived electricity demand in the 45 days after each SSW onset.
• Attribution for 2018: Used SNAPSI ensemble forecasts with two stratospheric nudging setups (nudged to the observed SSW evolution vs. nudged to climatology). This isolates the causal contribution of the anomalous stratospheric state to surface temperatures and, via the demand model, to electricity demand extremes.

Broader Context

The paper emphasises that SSWs are one of the few sources of subseasonal- to- seasonal (S2S) predictability and that linking them explicitly to energy-system impacts (rather than just temperature) is novel. It also discusses the value of forecast- based attribution approaches for impact studies.

Title: The Influence of Sudden Stratospheric Warmings on Extreme European Electricity Demand

Journal:  Meteorological Applications (Volume 33, Issue 5, e70241)

DOI: 10.1002/met.70241

Published: 8 October 2026

Provided: University of Exeter

ABSTRACT

Sudden stratospheric warmings (SSWs) provide a source of surface predictability up to several weeks in advance. They generally precede cold weather across the northern midlatitudes, including extremes. When it is cold, demand for heating typically increases electricity demand. We use reanalysis data and a weather-driven demand model for various European countries to investigate the relationship between SSWs and extreme electricity demand. We find that extreme demand of ~120% of climatology is 1.5–3 times more likely in periods following SSWs across northern and central Europe. We then use subseasonal forecast experiments from the Stratospheric Nudging and Predictable Surface Impacts project to explicitly attribute the impact of the February 2018 SSW, an event that preceded a cold weather outbreak across Europe. These experiments include nudging of the stratospheric state to either its observed or climatological evolution, allowing the causal impact of the SSW to be identified. We find a robust simulated increase in extreme demand risk attributed to the 2018 event. This indicates a window of opportunity for earlier prediction of extreme European electricity demand risks following SSWs.