Monthly review August 2022

The last summer month of August was 3.3 degrees too warm in our region compared to the
climate reference period 1961-1990, with a mean temperature of just under 21 °C. It was the
6th warmest August since 1961. In the months of August, the air temperature in Dresden has
already risen by an average of 2.7 K in the period 1961-2022.
The sun shone for a total of 237 hours. This corresponds to an increase of 41 hours. In the
months of August, the sunshine duration in Dresden increased by an average of 44 hours in
the period 1961-2022.

After the record drought observed from March to July, this continued even more strongly in
the first two decades of August. By 20 August, the drought situation had even worsened
considerably and plants that had not yet died were exposed everywhere to the most
extreme drought and, at times, heat stress. Nevertheless, thanks to two heavy precipitation
events on 20 and 27 August in Coswig, August ended with a positive precipitation balance.
On the 27th alone, intensive heavy rainfall without the involvement of thunderstorms in the
Coswig area led to a rainfall amount of approx. 50 mm within 2 hours (Fig.1).

The sum of all individual precipitation measurements in Coswig in August was 87.8 mm. This
was 121 % of the reference value for this month. The previous negative annual precipitation
balance in 2022 was thus reduced by 15 mm to a minus of still 120 mm. The drought
situation in the deeper soil layers down to a depth of 1.8 m could not be alleviated in any
way by the abundant precipitation in the last third of the month. Only the topsoil down to a
depth of about 25 cm was sufficiently soaked, which meant a rescue in the greatest need for
many plants and animals. Our landscape became green again, clearly demonstrating the high
value of rain to everyone. It is high time to put the fairy tale of the so-called "bad weather" to rest.

Weather in Saxony in spring and summer 2022:

There were several advances of subtropical air masses, most of which were rather dry in
character or repeatedly came under the stubbornly dominant influence of high pressure,
which is why they quickly dried out due to sinking air movements. Thus, although
temperatures above 30°C often caused a feeling of intense heat stress, the unpleasant
feeling of sultriness was seldom experienced here in Saxony. Once certain weather situations
had set in, they lasted for an unusually long time. There was a complete lack of the
previously characteristic changeability of our weather.

In many European countries this year there is a drought such as has not been observed for
several centuries. Even in our country, the accumulation of drought years since 2018 (with
the exception of 2021) is without precedent, as available records since 1761 show us quite
clearly. Without going into scientific details here, it is only worth mentioning that as a result
of global warming (here: Arctic) the "jet stream" has clearly changed its former typical characteristics. As a consequence, hitherto unknown and strongly pronounced extremes are also occurring in Europe.

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Fig.1: The map shows 3 regions affected by heavy rainfall on 27.8.2022 (blue colouring). The core of the small-scale cluster northwest of Dresden was over Coswig. Between 40 and more than 50 mm fell in a short time. The precipitation was caused by a quasi-stationary air mass boundary from the Baltic Sea to the Mediterranean Sea, which separated cooler air in the west from warm and humid air masses in the east (image source: unwetterzentrale.de).

Autor: Wilfried Küchler