Why Belgian Electricity Prices Hit €1,038/MWh: Inside Europe's Heatwave-Driven Energy Crisis

Belgian wholesale electricity prices surged past €1,000/MWh during the June–July 2025 European heatwave due to a classic demand-supply squeeze: extreme heat (over 40°C in parts of Europe) drove up air-conditioning demand, while at the same time thermal and nuclear power plants suffered outages or deratings because high river temperatures reduced cooling-water availability. Several other European markets also set multi-year or all-time records for price spikes. The broader picture reveals structural vulnerabilities in supply, a market outlook shaped by the rapid expansion of solar and batteries, and rising energy-security concerns over the resilience of thermal generation fleets during extreme weather events.

Why Belgian prices hit €1,038.25/MWh

• Record wholesale price. On a Wednesday in late June 2025, to secure electricity at 20:45, the Belgian day-ahead wholesale price reached €1,038.25/MWh — the highest in many years and a six-year record for the country .
• Demand spike. The European heatwave pushed daily electricity demand up by as much as 14% across affected countries, driven overwhelmingly by air-conditioner and fan usage .
• Supply-side failures. Simultaneously, extreme heat caused outages at thermal power plants and reduced nuclear output (because cooling-water intake temperatures exceeded regulatory limits or cooling efficiency fell) . High temperatures also impaired hydropower availability in some regions .
• Timing and solar's role. The peak at 20:45 came after solar generation had fallen off for the day, removing the large daytime solar cushion that had kept midday prices much lower. During the hottest hours, solar output was at record levels (EU solar generation hit 45 TWh in June 2025), but that abundance did not persist into the evening peak, when demand remained high and flexible supply was scarce .

Other European markets that set new records

• Belgium & Netherlands. On 1 July 2025, Belgian and Dutch hourly prices hit €517.57/MWh at 20:00 — already extremely high before the later €1,038 spike .
• France. French power prices rose sharply on warnings that heat would force nuclear output cuts, contributing to 175%+ price surges across affected European markets .
• Greece. In late September 2025, Greek day-ahead prices surged 34.5% in a single day, averaging €141.58/MWh and hitting €425.83/MWh at peak hours — one of the steepest recorded spikes .
• Italy and Spain. Mainland Spain and Italy registered the highest daily electricity demand so far in 2025 during the heatwave .
• General pattern. Multiple analyses by Ember, Montel Analytics, and AleaSoft confirmed that the June–July heatwave doubled average daily prices across most major European markets, with some markets seeing prices 2–3 times higher than typical .

Broader supply-and-demand factors

Factor	Detail
High gas prices	European gas storage was depleted after a cold Q1 2025, keeping wholesale gas prices elevated and setting a high marginal cost for gas-fired plants .
Low wind & hydro	Wind generation was below seasonal norms during parts of Q1–Q2 2025, and hydro output was lower than the previous year .
Nuclear constraints	French nuclear output faced heat-related curtailments; Belgian nuclear output also declined year-on-year .
Solar boom	Solar capacity additions continued rapidly; June 2025 was the highest-EU-solar-generation month on record (45 TWh). This depressed daytime prices sharply but did not prevent evening peaks .
Belgian grid reliance on imports	Belgium is a net importer during peak hours, and its declining domestic dispatchable capacity (gas and nuclear retirements) makes it acutely exposed to simultaneous stress across neighbouring markets .

Market outlook and energy security concerns

• Short-term outlook. The European Commission's Q1 2025 quarterly report noted that after a harsh winter quarter, prices began to ease in spring thanks to higher renewables output and declining gas prices . Q3 2025 saw a surge in negative-price hours (over 500 hours in the Netherlands, Spain, and Sweden) as record solar and wind output coincided with weak demand . This points to a growing intra-day price divergence — cheap (often negative) at solar peak, extremely expensive in the evening shoulder hours.
• Energy security concerns raised.
  • Vulnerability of thermal & nuclear to heat stress. The heatwave exposed that Europe's thermal generation fleet is increasingly susceptible to summer heat extremes, which can force unplanned outages precisely when demand spikes .
  • Need for flexible assets and storage. Energy think tanks and grid operators (e.g., Elia, Belgium's TSO) have warned that the growing share of weather-dependent renewables — without commensurate growth in 24/7 dispatchable capacity, battery storage, and demand response — heightens the risk of evening price spikes during extreme weather .
  • Cross-border coupling risks. When Belgium, the Netherlands, France, and Germany all face simultaneous heatwave stress, there is limited surplus capacity to import, pushing prices in interconnected markets to co-spike .
  • Call for policy action. European Parliament questions have specifically asked the Commission how it plans to ensure the resilience of nuclear and thermal plants under rising temperatures, and whether grid adequacy assessments (ENTSO-E summer outlooks) adequately capture compounding weather risks .