An unusually intense early-season heat wave is bringing scorching temperatures to Western and Central Europe, with highs near or above 104 degrees Fahrenheit (40°C) recorded in parts of Spain and France over the weekend.

Why it matters: The World Meteorological Organization warned Friday that this heat wave is a preview of the future, as heat waves are starting earlier in the year and are becoming more frequent and severe as a result of human-caused climate change.

• Prolonged, extreme heat is deadly, especially for vulnerable populations like the elderly, infants, children and people with chronic diseases.

By the numbers: Spain's meteorological agency said Friday that it was the earliest heat wave in over 40 years, while France's weather service said it was the earliest ever to hit the country.

• Biarritz, France, broke its all-time heat record on Saturday with a high of 109.2°F (42.9°C), according to meteorologist Scott Duncan. That exceeded its previous all-time record by 4.14°F, which itself is unusual, since typically such long-term records are broken by smaller margins.
• On Saturday, a staggering 203 monthly high-temperature records were beaten or tied in France, along with 18 records for the hottest temperature observed for any day of the year, according to extreme weather specialist Maximiliano Herrera.
• The nation's hottest temperature on Saturday was 110.1°F (43.4°C) at Pissos, in southwestern Franc,e where "red" warnings were in place for extreme heat.

Zoom in: In a post on Twitter, Herrera described the heat wave as "catastrophic" due to its intensity.

• Monthly heat records were also broken in Switzerland and Germany on Saturday, according to Herrera.
• Spain's weather service said temperatures could reach maximum temperatures of 107°F (42°C) in the northeast Saturday, while large parts of the country could reach a maximum of around 104°F (40°C).
• At San Sebastien, Spain, along the Bay of Biscay, the high on Saturday reached 110.3°F (43.5°C), for an all-time record, Herrera tweeted.
• Météo-France said that multiple weather stations across the country recorded temperatures that broke heat records on Friday as well.

🌡️ #VaguedeChaleur

⬇️ Valeurs #records (à 17h), ce #vendredi 17/06 ⬇️

🔴40.4°C à CARCASSONNE (Aude, ouverte en 1948), précédent record 39.8°C le 21/06/2003
🔴40°C à SAINTES (Charente-Maritime, ouverte en 1916), précédent record 39.1°C le 29/06/1950

— Météo-France (@meteofrance) June 17, 2022

Our thought bubble: This heat wave is shattering all-time records during a time of year that is not the seasonal peak, which may exacerbate its public health impacts since people are not yet accustomed to mid-summer temperatures.

• Climate change is making extreme heat events far more likely and severe, with several heat waves in Europe attributed in large part to human emissions of greenhouse gases.
• One of the first heat wave attribution studies, in fact, detailed the role that climate change played in a deadly heat wave in France that occurred in 2003.

The big picture: Amid the heat, forest fires have erupted in Catalonia, Spain.

• One near Baldomar, about 87 miles northeast of Barcelona, has burned around 2,470 acres after starting on Thursday, though several thousand acres are threatened.
• Other fires have broken out in Spain, Portugal, Italy and France as temperatures have soared.
• The high heat put much of Spain under high or extreme risk of wildfire on Saturday.

What's next: The heat is expected to subside in France on Sunday and move into Germany, though Spain, Poland and Austria will still have abnormally high temperatures for several days, according to the Washington Post.

Go deeper: Flooding kills at least 18 people in India, Bangladesh