Every year in mid-June, Emily Wu, who lives in Germany, plans a family trip before the summer's peak holiday season arrives. This year, after conducting a lot of research, she decided to take her 6-year-old son to the Spanish island of Majorca, famous for its beautiful sandy beaches and crystal clear waters.

"But I didn't expect the weather to be so hot," said Wu. "I searched the web and it said the weather is warm in June. I expected it to be 25 C to 30 C, but during our six-day stay, we experienced highs of over 35 C."

Days after Wu's family left Majorca, a 34-year-old Dutch tourist died from heatstroke while hiking near the inland town of Soller on June 26.

Wu said that when she returned to Germany she was expecting cooler weather, but was instead welcomed by a heat wave warning. In the last week of June, the historic town of Renningen, where she has lived for five years, issued an alert advising parents to take their children from school to home. The children were advised to stay inside and drink more water.

The extreme weather was caused by a "heat dome" that has shrouded Europe and stayed longer than previous years.

In Germany, Greece, and France, authorities have evacuated homes and dispatched water-bombing aircraft with firefighters to battle wildfires since June. Health experts have advised limiting outdoor working hours, and told deliverymen to avoid unnecessary travel during the day.