What changed by May 22, 2026?

By May 22, the forecast signal had become much clearer. The event is no longer just a distant model idea: western Europe is already entering the first major heat episode of the season. The background pattern shows a strengthening upper-level ridge pushing north from northwest Africa into Iberia, France, the UK and central Europe. This ridge is the engine of the heat dome.

The key detail is the speed of the reversal. Earlier in May, much of Europe experienced an unusually cool spell linked to Arctic air. Now the continent is moving quickly into a summer-like setup. In many places, the change may feel abrupt: from cool spring weather to strong sunshine, dry air, hot afternoons and warm urban nights in less than a week.

Why this is a heat dome, not just normal late-May warmth

A heat dome develops when a strong high-pressure ridge becomes established over a large region. Air inside the high pressure sinks, compresses and warms. Clouds are suppressed, rainfall becomes limited, and solar heating increases day after day. The effect is similar to placing a lid over a pot: heat builds underneath and has difficulty escaping.

In this case, the ridge is being fed by very warm air moving north from northwest Africa. That warm plume is expected to spread across Iberia first, then expand into western and central Europe. The result is a late-May temperature anomaly that may reach 10–15°C above normal in parts of western Europe.

Forecast by date: May 22–29, 2026

The hottest conditions will not arrive everywhere at once. The event begins over Iberia, peaks over western Europe through the weekend, then extends farther east during the final week of May. The exact eastern boundary remains uncertain, but the signal for above-normal temperatures is strong.

Spain and Portugal: the first and strongest heat zone

Spain and Portugal remain the leading hotspot of this event. Inland and southern areas are expected to see the highest temperatures, with forecast values widely in the low to mid-30s and locally reaching the upper 30s. For late May, these values are much closer to midsummer than to normal spring weather.

The most exposed areas are southern Spain, inland Andalusia, parts of Extremadura, inland Portugal and the lower valleys where heat can pool. Coastal areas may be moderated by sea breezes, but even there the sun angle is now high enough to create strong heat stress during the afternoon.

France: records may be challenged

France is one of the key countries to watch because the heat plume is expected to expand directly from Iberia into the southwest, west and eventually north of the country. Southwest France may see values in the low to mid-30s, while Paris and other northern cities may climb toward +30°C or higher.

The risk in France is not only high daytime temperature. Warm nights may become a problem in urban areas if the air mass remains stagnant. Cities such as Paris, Nantes, Bordeaux, Toulouse and Lyon may feel significantly hotter because of concrete, asphalt, limited nighttime cooling and the urban heat island effect.

United Kingdom and Ireland: unusual heat and health alerts

The United Kingdom is under a much stronger heat signal than is typical for late May. Southern England, the Midlands, East Anglia and London are expected to experience the highest values, with temperatures potentially reaching around +30…+33°C in the hottest spots. This is why heat-health alerts are important: the risk is not just the temperature itself, but the early timing of the event.

As of May 22, amber heat-health alerts are in force for several English regions, including London, the South East, East of England, East Midlands and West Midlands, with yellow alerts covering other parts of England. These alerts run through May 27, highlighting the possible strain on health and social care systems.

Ireland is expected to be warm but generally less extreme. Inland eastern and southeastern areas may approach the low to mid-20s, while Atlantic-facing coasts remain cooler due to the sea influence. Scotland and northern England should also be warmer than normal, though not as hot as southern England.

Germany, Benelux and central Europe: summer arrives fast

Germany, Belgium, the Netherlands and Luxembourg are expected to move into the warmer part of the event during the weekend and early next week. The first push will be strongest across western Germany, the Rhine corridor and Benelux, where temperatures may climb into the upper 20s and locally near +30°C.

By May 26–28, the warm air should spread deeper into central Europe. Czechia, Austria, Slovakia and Hungary may experience widespread above-normal temperatures. The most important uncertainty is storm development: if cooler or more humid air approaches from the north or west, the edge of the heat dome could become unstable.

Italy, the Alps and the Balkans: heat plus thunderstorm potential

Italy and the Balkans are likely to warm more clearly after the heat dome matures over western Europe. Northern Italy, the Po Valley, Slovenia, Croatia, Serbia, Bosnia and parts of the western Balkans may see temperatures in the upper 20s to low 30s later in the period.

The Alpine region is more complex. Valleys can become very warm, while mountain areas may act as thunderstorm triggers. If moist air is present, strong afternoon heating can lead to convective showers or storms near the Alps, northern Italy, Austria and the western Balkans.

Eastern Europe and Ukraine: warmer trend, but lower confidence

For eastern Europe, including Ukraine, the forecast is less certain than for western Europe because the core of the heat dome is expected to mature farther west first. However, by May 27–29, warmer-than-normal air may spread eastward into parts of Poland, Slovakia, Hungary, Romania, Moldova and western Ukraine.

The key question is how far east the ridge expands before Atlantic or northern European disturbances begin to weaken it. If the high-pressure zone remains strong, eastern Europe will see a more obvious warm-up. If the ridge shifts or breaks down earlier, the region may instead see a mix of warm air, cloudiness and thunderstorms.

Health risk: why this heat is dangerous even before summer

Late-May heat can be more dangerous than the same temperature in July because people are less acclimatized. Homes, schools, transport networks and workplaces may not yet be operating in full summer mode. Many people underestimate the sun strength, especially after a cool spell.

The highest risk is for older adults, young children, people with heart or respiratory conditions, outdoor workers, tourists and anyone attending large events. Warm nights are also important: if temperatures remain high overnight, the body has less time to recover from daytime heat stress.

Wildfire and drought concerns

The heat dome will increase evaporation and dry out surface vegetation, especially in areas that already had dry soil or limited recent rainfall. The wildfire risk is most important in Portugal, Spain, southern France, parts of Italy and the western Balkans. Even if the event lasts only several days, strong sun, hot air and local wind can quickly raise fire danger.

Farmers should also watch soil moisture. Warmth can accelerate crop growth after a cool period, but excessive heat and dry wind can stress young plants. Vineyards, orchards, vegetables and recently planted crops may require careful irrigation management, especially where rainfall has been limited.

Model comparison: what ECMWF and GFS agree on

As of May 22, the broad agreement between major forecast models is strong. Both ECMWF-type and GFS-type guidance support a major ridge over western Europe, a warm plume from northwest Africa and a period of unusually high temperatures across western and central Europe. The main disagreement is not whether the heat happens, but exactly where the hottest core sits and how long it persists.

Bottom line for Europe

As of May 22, 2026, Europe is facing a notable late-May heat dome event. The highest confidence is for Spain, Portugal, France, the UK, Benelux and western Germany, where abnormal warmth is already expected through the weekend and early next week. The strongest heat may reach +35…+38°C in Iberia and around +30…+33°C in parts of France and southern England.

The event is important because it arrives after a cool spring pattern and before many people are prepared for sustained summer heat. The main hazards are heat stress, wildfire risk, dry soils, urban overheating and localized thunderstorms near the edge of the hot air mass. The key advice is simple: treat this as a real early-season heat event, not just a pleasant warm weekend.