Hungary halts nuclear plant as Danube drought worsens amid heatwave

Herz — Climate Desk · 3 August 2026 at 10:12 · 30s summary · 3 min read

What we know

The heatwave that swept across Western Europe during the week of July 27, 2026, is now moving toward central and southern regions of the continent, according to The Guardian. Temperatures near 40°C are expected across wide areas, threatening several countries with an energy crisis.

Weather forecasts predict 37°C in Budapest and Vienna, two of the capitals most directly threatened.

In Hungary, the Danube's low water levels have immediate consequences for electricity production. The river no longer provides sufficient flow to cool the reactors at the Paks nuclear power plant within regulatory safety limits. Most of this plant's production—it is the country's only nuclear facility and supplies a large share of the nation's electricity—has been shut down since August 3, 2026.

This is the first time such a shutdown has occurred in 44 years. The Danube's level is expected to drop further in the coming days, with a complete shutdown of the plant expected before the end of the week.

Context: nuclear power and heatwaves, a known vulnerability

The Paks plant uses open-circuit cooling: it draws water from the Danube to cool its reactors, then returns it to the river at a higher temperature. During low-water periods—when a river's flow reaches its lowest level—the available volume may become insufficient to meet regulatory safety thresholds, forcing the plant to reduce or halt production.

This interdependence between heatwaves, drought, and nuclear production has already emerged in Europe. In summer 2003, several French and German nuclear plants had to reduce their output because temperatures in the Rhône, Loire, and Moselle rivers exceeded permitted thermal discharge thresholds.

In 2022, a record drought forced EDF to reduce or shut down multiple reactors in France. This phenomenon worsened an already fragile availability crisis in the French nuclear fleet, driving electricity prices up across Europe.

Timeline

1. Summer 2003
   A European heatwave forces several French and German nuclear plants to reduce output. Temperatures in the Rhône, Loire, and Moselle rivers exceed regulatory thermal discharge limits.
2. Summer 2022
   A record drought combined with a heatwave forces EDF to reduce or shut down multiple reactors in France. Electricity prices spike across Europe.
3. An intense heatwave strikes Western Europe with record temperatures in multiple countries.