Overview
- The stalled high-pressure pattern known as an omega block has parked hot, dry air over large parts of Western Europe, pushing daytime temperatures above 40°C and near 44°C in some spots and contributing to more than 50 deaths in France.
- An omega block forms when the jet stream weakens and large north–south Rossby waves trap a high-pressure ridge between two lows, forcing air down, clearing clouds and trapping heat over the same region for days to weeks.
- A World Weather Attribution analysis released on 26 June concluded this heat episode would have been virtually impossible without human-caused climate change and that unusually warm night-time temperatures are now far more likely.
- Cities are facing worse conditions because urban heat islands and waste heat from air conditioners amplify surface temperatures, and hospitals and emergency services in the region are reporting severe strain.
- Meteorological agencies say the block could hold for days to weeks unless a strong upstream storm breaks it, and scientists are continuing to study whether blocking patterns themselves are becoming more common as the climate warms.