Northern Germany sweats through record June heatwave as wildfire risk spikes to level 4

Temperature forecast and warnings

A powerful high-pressure system named “Hartmut” is driving the strongest June heatwave ever recorded across northern Germany. The German Weather Service (DWD) has issued heat warnings for Hamburg, Schleswig-Holstein, Lower Saxony, and Mecklenburg-Western Pomerania. On Friday inland temperatures are forecast to climb to 36°C in Hamburg and Schleswig-Holstein and up to 38°C in Lower Saxony. Saturday is expected to become the hottest day, with values reaching 39°C inland and 26 to 31°C along the coasts. The DWD describes the air mass as very humid and unstable, meaning any thunderstorms that develop will immediately become severe.

This is the strongest heatwave we have ever seen in June. It has never been this hot this early and for such a long period.

The previous June temperature record for northern Germany was set on 20 July 2022, when Hamburg measured 40.1°C and the Lower Saxony station at Barsinghausen-Hohenborstel logged 40.0°C. Meteorologists say those records could be challenged this weekend. Sea surface temperatures along the North Sea coast are currently 18 to 19°C and along the Baltic Sea 17 to 20°C, roughly two to three degrees above the seasonal average.

Wildfire danger and precautions

As the heatwave intensifies, the wildfire danger level in Schleswig-Holstein has been lifted to 4 on a scale of 5, the second-highest warning, with a rising trend. “Persistent drought and high temperatures mean that fires on fields, meadows or in forests can spread extremely quickly. Often small carelessness is enough to trigger a blaze,” said state fire chief Jörg Nero. He urged the public to refrain from lighting any open fires near forests and to avoid discarding cigarette butts into nature.

More than 90 percent of forest fires are caused by people, either deliberately or through negligence.

Foresters also ask visitors not to park cars on dry vegetation, to keep rescue access roads free, and to never leave glass bottles or shards behind. Huma noted that the structurally rich mixed forests with a high proportion of deciduous trees maintained by the state forestry service are the best fire prevention strategy, and that close cooperation with local fire brigades has kept major blazes at bay for the past decade.

Event cancellations and health advice

Several outdoor events in Schleswig-Holstein and Hamburg have been cancelled because of the extreme conditions. A girls’ football tournament in Osterrönfeld, an agility competition in Brunsbek, and the village festival in Wohltorf will not take place. The Hamburg half marathon scheduled for Sunday has also been called off. Organisers who are going ahead are deploying lawn sprinklers and extra drinking-water stations.

Health authorities remind residents to drink at least two liters of water evenly throughout the day, to avoid staying outdoors during the hottest afternoon hours, and to favour lukewarm or lightly chilled drinks over ice-cold beverages. Alcohol and sugary drinks should be avoided because they place additional strain on the circulatory system. Pregnant women, the elderly, young children, and people with chronic illnesses face the highest risk. Forest animals are also suffering: amphibians and young wildlife are particularly affected as water points dry up, although deer and wild boar can adapt by seeking shady areas.

Climate context

Data from the German Environment Agency show that the average number of days above 30°C in Germany has risen despite large year-to-year fluctuations, a trend that is firmly linked to climate change. The World Weather Attribution initiative has repeatedly demonstrated that heatwaves worldwide have become more intense and more likely because of human-caused warming. Northern Germany’s current heatwave fits into this longer-term pattern.