What is an Omega Block? Weather pattern behind Europe's extreme heatwave

Europe is currently experiencing an intense heatwave and 40 people have drowned in France only, as they tried to get rid of scorching heat.

Meteorologists have identified a rare atmospheric pattern known as “Omega block” as one of the main reasons temperatures are staying dangerously high for days or even weeks.

The name of the pattern comes from the shape of a Greek Letter Ω (Omega).

What exactly is an Omega block?

An Omega block is a large, slow-moving weather pattern in the atmosphere that gets “stuck” in one place.

It forms when:

• a high-pressure system sits in the middle
• two low-pressure systems sit on both sides

This creates a stable “blocking” pattern in the jet stream, the fast air current that usually moves weather systems across continents. Because of this blockage, normal weather patterns cannot move freely.

The high-pressure system acts like a lid over the atmosphere. It pushes clouds away, prevents rain from forming and traps warm air over the same region for several days or even weeks. That is why temperatures keep rising instead of cooling down.

Normally, weather changes every few days as air systems move across continents. But during an Omega block, the flow becomes stuck, so the same hot conditions remain in place for a long time. This is what makes heatwaves more extreme and longer lasting than usual.

Meteorologists say this pattern can be especially dangerous in summer because it increases the risk of drought, heat stress and wildfires. Once the pattern finally breaks, the weather can shift quickly, sometimes bringing sudden storms or heavy rain.

To put the concept in perspective, an Omega block is like a traffic jam in the sky. It stops weather from moving and when it forms over a place like Europe, it can lock in extreme heat until the pattern changes.