Germany had its hottest day of the year on Thursday, according to the National Meteorological Service (DWD) with the mercury topping 32 degrees Celsius (90 degrees Fahrenheit) in Berlin and 37 degrees Celsius in the city of Cologne, in western Germany.

Unrelenting sunshine has hit most of the country and a spring drought continues. Northern Germany faces the threat of wildfires. In Potsdam, just west of Berlin, a wildfire engulfed 90 hectares (222 acres) on Thursday and triggered warning for possible evacuations in the community of Fichtenwalde, where 2,800 people live.

A firefighter worked quickly to contain the wildfire in Potsdam

Drivers have had to slow down on many of the country's highways. To avoid road accidents, triggered by the stress that excessive heat can cause to fast-moving vehicles, authorites have implemented temporary speed limits. On the A81 expressway, which runs along western Germany and through the city of Stuttgart, authorities have set a maximum driving limit of 80 kilometers (50 miles) per hour.

City fountains help citizens keep cool in Cologne's extreme heat

Water a refuge? Not so fast

This weekend, many Germans are likely to hit the various lakes and reservoirs that dot their country's landscape, in search of a reprieve from the oppressive heat. But they will have to be cautious, warmer waters have caused an increase in harmful bacteria and algae in stagnant waters.

In the northeastern state of Mecklenburg-West Pomerania the growth of blue-green algae has been reported, which can cause irritation of the skin and of the mucus membranes. In Lake Müritz, on the southern end of the state, the cercaria parasite has been detected, which causes skin rashes and can last several days.

Read more: What you need to know about climate change

Rhine River affected

The lingering spring drought has driven the Rhine River and its tributaries to dangerously low levels, disrupting transportation of goods in this vital waterway. Restrictions in shipping are already in place in the upper Rhine.

According to the Mannheim office of the federal Waterway and Shipping Department, ships can only be loaded on the river with 1,500 tons of cargo, down from their usual weight of 3,000 or more.

Low water levels in the Rhine River disrupt transportation of goods

High water temperatures are also posing a serious threat to the fish population in the Rhine. Between Lake Constance and the Swiss town of Schaffhausen, where the river flows just before it makes its way north to German territory, the temperature of the water has hit 25 degrees Celsius. The fish in the area can die at 27 degrees.

Up north in the state of Rhineland-Palatinate, heat emitted into the water by various power plants is contributing to the dangerous 28-degree point in the Rhine.

The federal Environment and Nature Conservation Administration has warned that death is not the only threat for fish in the river. Warm waters also delay their migration, as they deviate from their path in search of colder streams, and that could threaten their nesting patterns. For this reason, the environmental department is asking states to implement controls on power plants for the time being, in an attempt to stop the rising temperatures.

Read more: Will extreme weather become even deadlier?

No end in sight

According to weather forecasts, Germans will have to brace for a prolonged heat wave with no end in sight. On Friday, temperatures are supposed to remain as high as Thursday or perhaps a bit higher. Temperatures are forecasted to hover around 30 degrees for the next week in the hottest areas, such as western Germany.

jcg/rt (DPA, AFP)

Germany's heat wave: Shining sun and burning fields Unusually dry In northeastern Germany, there has been hardly any rainfall in recent months. The country's weather service says Saxony-Anhalt received just 15 liters of rainfall per square meter — roughly a quarter of the average. Across Germany, there were just 50 liters of rainfall per square meter, half of the usual amount. Mecklenburg-West Pomerania received more sunshine than any other German state.

Germany's heat wave: Shining sun and burning fields Unpredictable weather The little rain that fell came down very unevenly across Germany. In May, the country's weather service warned of potential forest fires in parts of Lower Saxony. Meanwhile in southwestern Germany, some towns faced torrential rains that flooded cellars and roads, such as here in Fischbach, Rhineland-Palatinate.

Germany's heat wave: Shining sun and burning fields Fire alert! The danger of forest fires is extremely high right now throughout the country. The state of Brandenburg faces the biggest threat. In recent weeks, authorities have been forced to put out more than 100 fires. Recently, 100 hectares of forest and wheat crops burned to the ground in the Oder-Spree region. Brandenburg authorities reported that 90 percent of fires are inadvertently caused by humans.

Germany's heat wave: Shining sun and burning fields Busy times for firefighters It took 40 firefighters 13 hours to extinguish the flames sweeping through Brandenburg's Oder-Spree region. A fire in Rostock, meanwhile, was not caused by humans — but by a bird. Police say the animal caused an electricity cable to short circuit, which then set a nearby field ablaze.

Germany's heat wave: Shining sun and burning fields Tapping into new sources Saxony-Anhalt's firefighters, meanwhile, are so busy they needed to get creative to find new sources of water. So they headed to a nearby pool to refill their tanks. The dryness, meanwhile, not only makes fires more likely but also poses a major threat to farmers.

Germany's heat wave: Shining sun and burning fields Early harvests, low yields The unusually dry weather has forced many farmers to harvest their crops early. The German Farmers' Association has stated that even April was too warm and dry. The following months meant wheat crops ripened much faster than expected, though insufficient rain has produced a low yield. Sudden torrential rainfall, meanwhile, made matters worse by destroying parts of the crops.

Germany's heat wave: Shining sun and burning fields Crop failures on the cards Potatoes, sugar cane and corn are usually harvested in autumn. They require much more water than wheat and rapeseed. So due to the unusually dry weather, Germany's corn plants are in bad shape. The German Farmers' Association president, Joachim Rukwied, is pessimistic and fears crop failures could jeopardize the livelihoods of many farmers.

Germany's heat wave: Shining sun and burning fields No water in sight There are two kind of drought: "Drought in a meteorological sense refers to a drop in rainfall within one month below the long-term average," says Stephan Tober of the Helmholtz Center for Environmental Research. This causes a drought in the agricultural sense, meaning that there is too little water in the ground. That's a problem for wheat and meadows on the banks of river Elbe here in Dresden.

Germany's heat wave: Shining sun and burning fields Vegetation adapts to heat "Extreme dry spells can cause long-term damage to trees and recovery takes a long time," says Ingolf Kühn of the Helmholtz Center for Environmental Research. Vegetation has a memory, so to speak, and may adapt if there are several consecutive years with little rainfall. Some German cities have now called on residents to help out in watering trees, so that some day, cacti will not replace trees.

Germany's heat wave: Shining sun and burning fields Problems on the River Rhine The Rhine River and its tributaries have lowered to dangerous levels, leading to restrictions in shipping. The Mannheim office of the federal Waterway and Shipping Department confirmed that, until conditions change, ships in the upper Rhine can only be loaded with 1500 tons of cargo, down from their usual weight of 3000 or more. Author: Julia Vergin



Each evening at 1830 UTC, DW's editors send out a selection of the day's hard news and quality feature journalism. You can sign up to receive it directly here.