We asked AI for GFS ensembles and upcoming heatwaves in Europe: What does it forecast for countries in Europe, following the legendary +41.6°C in Spain in May?
Marek Kučera 
As Europe braces for another wave of extreme heat in the coming two weeks, the risks posed by soaring temperatures are becoming increasingly severe. Forecasts indicate local maximum temperatures potentially exceeding almost 40°C in southernmost parts of continental Europe, with heatwaves extending from the Iberian Peninsula through France, Italy, and the Balkans.
These conditions present multifaceted risks — not only to public health but also to infrastructure, agriculture, and ecosystems — demanding urgent preparedness and adaptation.
Southern Europe is experiencing unprecedented heat, with El Granado in Spain recording 41.6°C on May 30, 2025—the highest May temperature ever documented in the country. In Portugal, Coruche and Alvega reached 39.9°C on May 29, just 0.1°C shy of the national May record. France’s Bégaar also set a new May record with 37.0°C.
Looking ahead, GFS model projections from wetterzentrale.de indicate that parts of southern Spain and Portugal could experience temperatures up to 45°C in the first half of June.
The heatwave exacerbates existing drought conditions across Europe. Over 40% of the continent is currently experiencing drought, with significant impacts in northern and western regions, including the UK and Ireland. In north-west England, a drought has been officially declared due to severely low water levels in reservoirs and rivers.
Additionally, the combination of extreme heat and dry conditions increases the risk of severe storms. Meteorological forecasts suggest that parts of France and central Europe may experience thunderstorms in the coming weeks, potentially leading to flash floods and other hazards.
Wildfire Outlook for Europe (Next 2 Weeks)
As Europe enters early summer, the combination of high temperatures, prolonged drought in parts of southern and southeastern Europe, and dry vegetation is creating favorable conditions for wildfires. The highest wildfire risk is concentrated in:
- Southern Iberian Peninsula (Spain and Portugal): Especially Andalusia and Alentejo, where recent drought and heatwaves have dried out forests and scrublands.
- Southern France: Regions such as Occitanie and Provence are increasingly vulnerable, with low soil moisture and strong daytime heating.
- Italy: Particularly Sicily, Sardinia, and southern mainland areas, where dryness and heat elevate fire danger.
- Balkans: Parts of Greece, Albania, and North Macedonia face heightened wildfire risk amid dry conditions and heat stress.
Authorities in these regions are on high alert, with firefighting resources pre-positioned and public warnings issued. Any lightning storms combined with dry fuels could ignite new fires, while human activities remain a common wildfire trigger.
Severe Storm and Tornado Forecast (Next 2 Weeks)
Although heatwaves dominate southern Europe, the risk of severe convective storms and tornadoes will be most pronounced in central and northern Europe due to contrasting air masses and atmospheric instability:
- Central Europe (Germany, Czech Republic, Poland, Austria): Forecasts indicate several episodes of strong thunderstorms between June 5 and June 12, with potential for large hail, damaging winds, and isolated tornadoes—especially in Bavaria, Saxony, and southern Poland.
- Northern Europe (Scandinavia, Baltic States): Thunderstorm activity is expected in southern Sweden, Finland, Estonia, and Latvia, particularly during mid-June, with some risk of severe gusts and hail. Tornado occurrences are rare but possible in highly unstable conditions.
- British Isles: Occasional thunderstorms with localized severe gusts and hail are forecast mainly in southern England and Ireland from June 7 onward.
These storms form along frontal boundaries where warm, moist air from the south clashes with cooler northern air masses. Although the most intense storms and tornadoes tend to be localized and short-lived, they pose hazards to life, infrastructure, and transport.
Extreme Heat Outlook in Europe – First Half of June 2025 according to GFS ensembles used by AI
Ensemble forecasting is a cutting-edge meteorological technique used to improve weather predictions by accounting for uncertainties inherent in initial atmospheric conditions and model physics. Instead of relying on a single forecast run, ensemble forecasting generates multiple simulations—called ensemble members—each with slightly varied starting conditions or model parameters. This creates a range of possible weather outcomes rather than one deterministic forecast.
(Based on hottest GFS ensemble member + adjustment)
Portugal:
- Extreme interior zones (Alentejo, Beja) could see surface maxima exceeding 44°C.
Spain:
- Southern and interior regions (Andalusia, Extremadura) may approach or surpass 45°C, especially around El Granado.
France:
- Warmest southern zones, including Occitanie and Provence, could hit 40–42°C locally.
Italy:
- Po Valley and southern inland areas, including Sicily, could reach 41–43°C in heat pockets.
Germany:
- Southern Bavaria and parts of Baden-Württemberg might locally reach 36–38°C.
Switzerland & Austria:
- Lowlands and eastern plains may experience maxima of 35–37°C.
Poland & Czechia:
- Southern parts could see 33–35°C, with the warmest clusters centered near Moravia and Silesia.
Slovakia & Hungary:
- Southern and central areas might reach 35–37°C locally.
Romania & Bulgaria:
- Southern plains and valleys could experience 38–40°C in isolated hotspots.
Greece & Balkan Peninsula:
- Inland and lower elevation areas likely to see 40–42°C, with some peaks possibly higher.
Baltics & Scandinavia:
- Generally cooler, but southern Baltic states could hit 30–32°C; southern Scandinavia might see 28–30°C under extreme runs.
British Isles:
- Southeastern England could approach 30°C in hottest ensemble runs.
Key Notes:
- These maxima are localized extremes forecasted by the single hottest ensemble member.
- Adjustment from 850 hPa temperature to surface max includes typical lapse rates plus local amplification effects.
- Such extreme temperatures often correlate with intense drought conditions and heatwave stress in vegetation, agriculture, and population health.
- These peaks represent the upper bound of temperature potential and not mean or widespread daily highs.
Expected Peak Timing of Heatwaves in Europe (Early June 2025) — GFS Forecast
Western Europe
- Portugal: Peak heatwave around June 3–5, especially in southern and interior regions (Alentejo).
- Spain: Peak expected June 3–6, strongest in Andalusia and Extremadura.
- France: Southern regions likely peak June 6–8, with maximum temperatures in Occitanie and Provence.
Central Europe
- Italy: Heatwave peak forecast for June 7–9, particularly in the Po Valley and southern inland areas.
- Germany: Southern regions expected to see peak heat June 8–10, mainly Bavaria and Baden-Württemberg.
- Switzerland & Austria: Peaks around June 8–10, especially in lowland and eastern areas.
Eastern Europe
- Poland: Peak heat likely June 9–11, focused in the south and central regions.
- Czech Republic: Heatwave climax expected June 9–11, especially southern areas near Brno.
- Slovakia: Peak heat around June 9–11, mainly southern and central zones.
- Hungary: Peak between June 8–11, with hottest conditions in central parts including Budapest.
- Romania: Peak heatwave forecast June 10–12, mainly southern plains.
- Bulgaria: Strongest heat expected June 10–12, particularly in northern regions.
- Greece: Peak temperatures projected June 10–13, focused inland in Thessaly and Macedonia.
Southeastern Europe
- Serbia: Peak heatwave forecast June 9–12, centered in central areas.
- North Macedonia: Heat peak expected June 10–12.
- Albania: Peak around June 10–13, inland zones particularly hot.
- Croatia: Heatwave peak forecast June 9–11, especially eastern Slavonia.
Northern Europe
- Lithuania, Latvia, Estonia: Peak heat expected June 7–9, with highest local temperatures in southern and central parts.
- Denmark: Warmest period likely June 7–9.
- Sweden, Norway, Finland: Southern regions to see peak heat June 7–10, with highest temperatures in southern Sweden and southeastern Norway.
British Isles
- United Kingdom: Peak heatwave forecast June 8–10, mainly southeastern England.
- Ireland: Highest temperatures expected June 8–10, especially in eastern counties.
Summary
- The earliest heatwave peaks are expected in the Iberian Peninsula (June 3–6).
- Southern and central Europe’s peak heat generally occurs a few days later, around June 7–12.
- Northern Europe and the British Isles experience more moderate peak heat during June 7–10.
These peak timings correspond to the days with highest local maxima from the hottest GFS runs, reflecting the potential for intense, though localized, heat events. As always, localized weather variations may shift these peaks slightly.
Health Risks
1. Heat-Related Illnesses and Mortality
- Heat exhaustion and heatstroke: Prolonged exposure to extreme heat can overwhelm the body’s ability to regulate temperature, leading to heat exhaustion and potentially fatal heatstroke. Vulnerable populations — such as the elderly, children, people with chronic illnesses, and outdoor workers — are at greatest risk.
- Cardiovascular and respiratory stress: High temperatures exacerbate cardiovascular and respiratory conditions by increasing the strain on the heart and lungs. Hospitals often report spikes in admissions during heatwaves.
- Dehydration and kidney damage: Heat stress can cause dehydration, impacting kidney function and increasing the risk of kidney stones and acute kidney injury.
- Mental health impacts: Heatwaves also have been linked to worsened mental health outcomes, including increased anxiety, irritability, and even higher suicide rates in some studies.
2. Urban Heat Island Effect
Cities experience amplified heat due to concrete surfaces and limited vegetation, leading to “urban heat islands.” Urban residents face higher temperatures than rural counterparts, increasing the risk of heat-related illnesses and mortality, especially in densely populated areas.
Infrastructure and Economic Risks
1. Energy Demand and Blackouts
- Increased cooling needs: Heatwaves cause soaring demand for air conditioning, stressing power grids. This raises the risk of energy shortages or blackouts, particularly if supply chains or infrastructure are already vulnerable.
- Infrastructure damage: Roads, railways, and bridges can suffer heat-related damage such as buckling and melting of asphalt or rail tracks, disrupting transportation and logistics.
2. Agricultural Impacts
- Crop stress and yield reduction: Prolonged heat and drought stress crops, reducing yields of staples like wheat, maize, and vegetables. Heatwaves during flowering or grain-filling stages can devastate harvests.
- Livestock health: Animals are also vulnerable to heat stress, which can reduce productivity and increase mortality.
Environmental and Ecological Risks
1. Drought and Wildfires
- The ongoing dry conditions combined with extreme heat elevate wildfire risks across southern and central Europe. Recent heatwaves have already triggered early wildfire outbreaks in Spain and Portugal.
- Drought conditions strain freshwater resources, affecting ecosystems and human water supply.
2. Biodiversity Threats
- Heatwaves disrupt natural habitats and can lead to increased mortality among sensitive species, altering ecosystem balance.
Illustration photo: https://www.nbcnews.com/science/science-news/extreme-heat-dome-midwest-temperatures-hot-weather-rcna101153
