Updated European weather outlook until April 2025

A major sudden stratospheric warming event (SSW) will occur around the 9th of March, likely a displacement of the Stratospheric Polar Vortex (SPV) off the North Pole. This brings uncertain consequences in the medium and longer range.

The latest ECMWF weather regime probability forecast (see below) initially shows a positive North Atlantic Oscillation (NAO) pattern, followed by a stronger European high-pressure blocking. There will be a few days with a predominantly negative NAO pattern, or an Atlantic ridge, with high pressure near Iceland into Greenland starting the 10th of March week. It also shows a recurring positive NAO background flow beyond mid-March.

 

While the outlook suggests larger parts of Europe will end up milder-than-usual, confidence in warmer-than-normal temperatures is higher across northern and north-eastern parts of Europe. Elsewhere, temperatures could be closer to the seasonal average or temporarily even below average. Somewhat drier and calmer periods seem a little more likely, e.g. across the UK and parts of western and central Europe. By contrast, occasional wetter and windier periods are expected in southern areas, including parts of the Mediterranean region.

Later in March and especially in April, the major-SSW around the 9^th of March and/or an even earlier than usual final warming of the stratosphere (FSW) could lead to more frequent high latitude high-pressure blocks in the North Atlantic-Greenland sector, along with negative NAO and/or negative Arctic Oscillation (AO) or a Greenland High (GH) regime, posing a risk of colder weather in other parts, such as suspicious e.g. parts of the United Kingdom and Western and Central Europe. Given this trend, the less positive or near average temperature anomalies in these parts of mainland Europe seem plausible.

However, no ideal coupling between stratosphere and troposphere is predicted, confirming that cooler or colder periods are likely, but there is also the possibility that positive NAO patterns may return later in March and April, with the well-known wet and windy but mostly mild Atlantic flow. So, there are some opposing trends on the table.

Furthermore, it remains unclear whether the SPV could recover later in March and how good the troposphere-stratosphere coupling will eventually work out, see GEFS forecast of zonal mean u (m/s), shown as vertical section.

During displacement events, positive height anomalies are less likely to fully propagate down into the Arctic troposphere, in line with some recent research papers. In view of this, it is debatable to what extent the Major SSW could have sustained consequences later on.

Source: ECMWF

 

Source: GFS via Stratobserve.com

 

The latest temperature, precipitation, and wind departure forecasts for April are below.

 

Bottom line

Cooler or colder spells possible later in March and April, with often calmer and drier (good solar outputs as well) or close average precipitation, including also the risk of sharper late Arctic cold air outbreaks (with negative NAO). However, it could get wetter and windier at times (especially across north-western and north-/north-eastern portions of Europe), in line with an Atlantic flow pattern (positive NAO) returning at times. Occasionally wet also in parts of South Europe and the Mediterranean region.

 

About the author

Dr. Jens Bonewitz

Dr. Jens Bonewitz is an experienced long-range energy meteorologist at DTN. He consults with utility and renewable energy clients to help plan and prepare for the impact of weather. He combines research and its practical applications to produce meaningful weather forecasts within the S2S range.