A heatwave turned off the power to about 68,000 homes in northwestern France on Wednesday, marking the first major blackout of this heat event in the region, according to Asharq Al-Awsat and NDTV.

This part of France is normally cooler and quieter than other regions. Most homes there don't have air conditioning — people rarely need it. But when a record heatwave arrives, everything changes. Suddenly, air conditioners that haven't run all year switch on everywhere at once. It's like every door in a building opening at the same time: the electrical system, built for normal traffic flow, gets overwhelmed. Transformers — the devices that step electricity down to household-safe levels — overheat or shut themselves down automatically to avoid catching fire.

France's power comes from two main sources. Local utility companies like Enedis deliver power directly to your home. Separate transmission companies move electricity across long distances on high-voltage lines. When heat causes blackouts, it usually starts in the local delivery network, not at power plants. France generates much of its electricity from nuclear reactors, which produce about 70 percent of the country's power. But nuclear plants have a hidden heat problem: they pump river water through to cool their reactors, then release it back. When rivers get too warm, environmental rules stop plants from dumping that hot water, forcing them to reduce power — right when air conditioning demand spikes.

Across Europe this summer, power grids everywhere are under strain. Countries share electricity across borders like neighbors sharing power cords. When one country demands extra power, it pulls from neighboring nations, tightening supply everywhere. France usually sells power to other countries, but extreme heat can flip that around in weeks. It happened in 2003 and again in 2019.

A blackout during dangerous heat hurts the most vulnerable people: older adults, those with serious illnesses, and people in buildings that trap heat. That's why France built formal emergency plans after 2003, when a heatwave killed about 15,000 people across the country. Those plans guide how local authorities respond now. But their success depends on restoring power quickly — and nobody yet knows how long these repairs will take.

Sixty-eight thousand homes without power is serious, though it has happened before during European heat waves. The key questions right now: How fast will the lights come back on? Is the blackout spreading? And how hot are these homes getting? Those answers aren't yet clear.