A marine heat wave in the Mediterranean Sea is combining with a powerful heat dome to cause Europe to swelter under a brutal early summer heat wave.
It’s a pattern that’s popping up frequently as the planet warms: The influence of Mediterranean marine heat waves has been more pronounced in recent summers, with the ocean heat playing a role in spiking temperatures on land, contributing to deadly floods and stoking devastating fires.
Water temperatures in the Mediterranean Sea are up to 9 degrees above average for this time of year amid a significant marine heat wave. The most intense warming is present in the western Mediterranean, including just south of France.
This is helping to cause high humidity to surge north and to keep temperatures elevated at night across the heat wave-affected regions.
The heat wave, which also involves hot air flowing north from Africa, is also reinforcing the marine heat wave in a feedback cycle.


Temperatures have broken records in Spain and Portugal as swaths of Europe brace for more records to fall through Wednesday as the heat wave intensifies.
The town of El Granado in Spain saw temperatures spike to 46 degrees Celsius (114.8 Fahrenheit) on Sunday, a new national record for June, according to Spain’s national meteorological service AEMET. Last month was Spain’s hottest June in recorded history, as temperatures “pulverized records,” Aemet said Tuesday.
In Portugal, a provisional temperature of 46.6 degrees Celsius (115.9 Fahrenheit) was recorded in the city of Mora, about 80 miles east of Lisbon, according to the country’s weather service IPMA, which would be a new national record for June.
Scorching heat is sweeping almost the entirety of France. Multiple towns and cities endured temperatures above 100 degrees on Monday, according to provisional recordings from Météo France.
A red heat wave warning, the highest designation, is in place for 16 French départements Tuesday, including Île-de-France, where Paris is located. The Eiffel Tower summit is closed to tourists Tuesday and Wednesday, with staff asking their would-be visitors to take precautions during the searing heat.
“We apologize for the inconvenience caused, Eiffel Tower staff wrote on the landmark’s website. “During this period of high temperatures, please remember to protect yourselves from the sun and stay hydrated regularly.”
The United Kingdom is also baking, currently enduring its second heat wave of the summer. Temperatures pushed above 90 degrees on Monday, making for very uncomfortable conditions in a country where fewer than 5% of homes have air conditioning.

“The current June-July heatwave is exposing millions of Europeans to high heat stress,” Samantha Burgess, strategic lead for climate at the European Centre for Medium-Range Weather Forecasting, said in a statement.
“The temperatures observed recently are more typical of the months of July and August and tend to only happen a few times each summer.”
Wildfires are sweeping several countries as the temperatures spike. Fires broke out Sunday in Aude, in the southwest of the country, burning nearly 400 acres. In Turkey, 50,000 people have been evacuated as firefighters tackle fierce blazes mostly in the western Izmir and Manisa provinces.
Temperature records are also poised to fall Tuesday and Wednesday in Germany as the heat dome expands east, and before a series of relief-providing cold fronts begin to swing into northwestern Europe from the west.
Human-caused climate change is causing heat waves to be more frequent, intense and long-lasting. Europe is the fastest-warming continent, and is warming at twice the rate of the rest of the world. Climate change is also leading to more frequent and intense marine heat waves.