After a brief cool spell, Germany may already be heading for the next heatwave. Meteorologists are tracking a stubborn pattern: as soon as the heat eases, high pressure quickly builds again.
After the brief cool spell, Germany initially remains on the cooler side of a high-pressure system. But the heat has not disappeared – it is currently gathering over Spain and France and could soon move back into Germany.
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"At the moment Germany is on the cold side of the high," explains meteorologist Dominik Jung. The hot air is staying for now to the west of Germany’s borders. Weather models, however, indicate that the Azores high will once again spread into central Europe. The first fringes of the warmth could therefore reach the west and southwest towards the end of next week.
Temperatures of "30 degrees and more could then be possible across large parts of the country". The earliest, optimistic scenario for a return of the heat would be "by next weekend at the latest". But that is not yet certain: first, a boundary between air masses could form over Germany. That would keep both the timing and strength of the next surge of warmth uncertain.
Cool-down feels more extreme than it is
After the heatwave, current temperatures feel unusually cool.
A north-westerly flow and an upper-level trough are pushing temperatures below the 30-degree mark in many places. Near thunderstorms they can even drop locally below 20 degrees. For the second half of July, though, this is more like normal to slightly below-average summer weather.
"The impression of cold is mainly created by the contrast with the extreme heat beforehand," Jung stresses.
What was truly exceptional was the preceding hot spell: at the end of June, temperatures of 41.7 degrees set new records in Germany. The heat-warning phase, lasting around twelve days, was also one of the longest since the DWD heat warning system was introduced in 2005.
Severe thunderstorms mainly in the south
The current change in the weather also increases the risk of intense thunderstorms. The south and south-east of Germany are particularly affected, especially the upland regions – above all Bavaria, Baden-Württemberg and parts of Saxony. Vigorous storms are also possible along the air-mass boundary that may set up across the centre of the country.
Forecasters warn that localised severe weather with torrential rain, hail and gale-force gusts is possible there. Thunderstorms may also develop in northern and central Germany, but they are generally expected to be less intense.
"Summer keeps snapping back"
What stands out this summer is the unusual persistence of the weather pattern: "As a meteorologist, what surprises me most is how stubborn the pattern is," says Jung. After each cool spell, the area of high pressure rebuilds astonishingly quickly.
"Summer almost keeps snapping back into heat mode."
Another striking feature are the strong fluctuations between individual weather models. Some runs have simulated extremely high values. At times, the American weather model has even produced outliers of up to 47 degrees – around 20 degrees above the average of many model calculations.
"You rarely see jumps like that. They show how much small disturbances in the atmosphere are currently making forecasting more difficult."
Longer-term trend stays warm and dry
Looking ahead to the coming weeks, the signal still points to a generally warm and dry trend. After this unsettled phase, many models expect high pressure to strengthen again.
From around 21 July, temperatures of between 28 and 34 degrees, and locally up to 38 degrees, are again possible. That would mean a return of heat days, desert-like days and tropical nights. At the same time, dryness could once more move into sharper focus in many regions.
However, long-range forecasts still come with considerable uncertainty. "A trend is not a pinpoint forecast," Jung explains. "Beyond a week, the spread is large." So the further ahead you look, the wider the range of model outcomes becomes.
Only one thing seems certain, and many will have guessed it: summer clearly has no intention of retreating.
