Scorching Heat for the Summer Solstice: The Dangerous Longevity of Europe’s New June Heatwave

While the meteorological summer has barely officially begun, the summer solstice is coming up this weekend. And it arrives in style, with a new massive, high-pressure Heat Dome settled over the continent. It will trap a stagnant layer of scorching-hot Saharan air and trigger an early-season heatwave of above-normal intensity from the Iberian Peninsula to the capitals of Western Europe. The soil in many regions remains exceptionally dry from a record-breaking hot spell Europe experienced in late May, which strips away the Earth’s natural ability to cool itself through evaporation. This will allow surface temperatures to skyrocket even faster through the remainder of June. The temperature forecast numbers are flashing red, with Portugal and Spain bracing for temperatures that could reach 45 °C (113 °F), while cities like Paris are facing extended, multi-day stretches in the upper 30s to low 40s, roughly 10 to 15 °C above seasonal averages. It will become extremely hot in France and parts of Western and Central Europe as the Heat Dome strengthens and expands northward and eastward over the weekend and into the following week. The driving force behind this pattern is similar to the one in May, a strengthening upper-level ridge building out of Northwest Africa and expanding across western and central Europe. The following animation delivers a quick overview. Before we dig into the details about the pattern evolution in Europe, lets examine what is the main driver behind these extensive warm waves and heatwaves in general. What is a Heat Dome?   When significant, record-breaking heatwaves occurred in Europe, the United States, and Canada in the past, the Heat Dome was a contributing factor. The heat dome is usually the dominant feature of summer weather patterns on both continents. We refer to this phenomenon as a heat dome when extremely high temperatures develop. Here’s how it works and why understanding it on a broader scale is essential. The upper-level ridge pattern, or very warm air mass in the higher altitudes, also known as the Upper High (or blocking High), usually forms the heat dome. This weather pattern brings high, and sometimes record-breaking, temperatures to the region below. This term is used when a broad area of high-pressure air parks over a large portion of the continent. If the event is remarkably stable and extreme, it usually lasts several days or weeks. The heat dome works like a lid on a pot. The extensive dome traps warm air at all levels underneath, with layers sinking toward the ground.