TOU-I-1: Coastal bathing temperatures

The time period in which seawater temperatures potentially make a bathing holiday on Germany’s North Sea and Baltic Sea coasts possible, is subject to major fluctuations from year to year. Usually in June suitable temperatures will set in which last into the month of October. The duration of such temperature conditions has been increasing significantly on North Sea and Baltic Sea coasts.

Warmer temperatures for coastal vacations

Many German people like to spend their vacations relaxing on a sunny beach. The most important holiday destination for Germans is therefore the Mediterranean region, which accounted for 38% of holiday trips in 2019 – before the Covid-19 pandemic –, as found by a FUR travel analysis¹⁹⁷. In particular, Spain, Italy and Turkey are popular travel destinations among Germans. Within Germany, apart from Bavaria, the coastal Länder of Mecklenburg-Western Pomerania, Schleswig-Holstein and Lower Saxony rank most highly. The travel behaviour of Germans during the Covid-19 pandemic underlines the attractiveness of coastal tourism. As far as travels abroad are concerned, especially all travel to Spain, Italy, Turkey, Portugal, Croatia and Greece increased once pandemic-related travel restrictions were removed in 2021¹⁹⁸. In Germany the market share of bed-nights in the coastal regions of the North Sea and Baltic Sea for 2020 and 2021 amounted to some 5 % more than the previous years’ level (cf. Indicator TOU-I-3).

As far as Germany is concerned, it is conceivable that beach and bathing holidays on the coast – as the typical form of summer tourism – might in general benefit from air and sea temperatures rising as a result of climate change. Owing to global warming, the bathing season might last longer, thus increasing the attractiveness of outdoor bathing locations. Evidence for a tendency towards higher sea temperatures in the coastal waters of the North Sea and Baltic Sea has already been provided in terms of measurements taken within the station network of the BSH. The annual mean temperature calculated for the entire surface of the North Sea, based on analyses conducted by BSH on a weekly basis, has increased by roughly 1 °C since the introduction of this analysis in 1968 (cf. Indicator KM-I-1).

In order to enable an estimate – based on sea water temperatures – of the potential for bathing tourism in coastal areas, the duration of the potential bathing period is illustrated as the number of so-called bathing days on which the daily mean of the sea water temperatures of German coastal waters of the North Sea and Baltic Sea exceed a threshold value of 15 °C. There is a criterion that has to be met for the first bathing day of a season which requires that the temperature – measured after exceeding the threshold value – does not drop again below a daily mean value of 14 °C. The last bathing day is the last day in a year, on which the water temperature is still above 15 °C.

The indicator is based on water temperatures which are measured almost continuously at BSH measuring stations in the German Bight (North Sea) and the BSH’s Kiel Lighthouse (Baltic Sea) at some distance from the coast. These measurements have the advantage that they are homogeneous and more independent of short-term influences than measurements taken right on the coast. The location of the measuring stations also played a role in selecting the threshold value for assessing the bathing temperature. The sea water temperatures taken in bathing waters at the coast tend to be higher than at measuring stations far from the coast thus signifying that upwards of this value – also due to stronger diurnal variations – the water is potentially suitable for bathing. For the purpose of comparison: In the hot year of 2018 the maximum value of the mean surface temperature of the North Sea amounted to 16.3 °C; with regard to the Baltic Sea this value amounted to 20 °C.¹⁹⁹ Near the coast the maximum water temperatures (daily mean) at individual stations was clearly higher: In Hörnum on the island of Sylt for instance, values of 24.5 °C and in Neustadt (Holstein) 26.0 °C were measured.

The two time series covered by the indicator have been rising since the beginning of the 1990s (North Sea) and since the end of the 1980s (Baltic Sea), indicating a significant trend. This signifies that the time period on North Sea and Baltic Sea coasts, with sea temperatures potentially suitable for bathing, is extending. In both of these coastal regions, the first potential bathing days occur earlier and earlier every year, while the last suitable days occur later and later, extending into autumn, indicating a significant trend. In parallel with the warmer water temperatures, the air temperatures are becoming more favourable too. This was indicated by developments at DWD measuring stations Norderney (North Sea) and Kiel-Holtenau (Baltic Sea) respectively: The average daily mean and highest values measured for the air temperature during the summer vacation months of June to September have been rising at both stations. The indicator shows signs that the determining climatic factors for tourism in German coastal regions are becoming more conducive to bathing. Nevertheless, higher seawater and air temperatures can also entail negative effects. For example, rising temperatures favour the occurrence of pathogens such as vibrions (cf. Indicator GE-I-7).

Generally speaking, there are a number of other factors that influence the attractiveness of the North Sea and Baltic Sea coasts as destinations for beach and bathing tourism. These include other meteorological parameters such as sunshine duration, air quality or bio-climatic conditions interacting with air temperature, wind, radiation conditions and humidity. Besides, the occurrence of algae and jellyfish play a role. In future, conditions influencing coastal tourism can be changed by rising sea levels, more frequent and more intensive storm surges as well as coastal erosion (cf. Indicator KM-I-2, KM-I-3, and KM-I-4).

Whether these changes will have positive or negative impacts on touristic demand or whether they will have any effect at all, will also depend on numerous other factors, such as current travel trends, demographic change or economic scenarios. So far it has not become evident that people making holiday plans consciously avoid the hot regions bordering the Mediterranean, choosing instead to visit more northerly climes. It is true that in the course of a supplementary questionnaire added to the population survey entitled ‘Environmental awareness in Germany’²⁰⁰ conducted in 2021, roughly two thirds of respondents stated that they were changing their leisure and holiday planning, for instance by avoiding strenuous activities in the heat or by shunning hot-temperature holiday regions, while another 10 % stated that they intended to do so in future. However, the renewed increase in demand for travel to Mediterranean countries outlined above – after the removal of travel restrictions related to Covid-19 – indicates that the desire for change has not been reflected in the actual travel plans made so far.

^{197 - FUR – Forschungsgemeinschaft Urlaub und Reisen e.V. (Hg.) 2022: RA ReiseAnalyse 2022. Erste ausgewählte Ergebnisse der 52. Reiseanalyse. Kile, 18 pp. https://reiseanalyse.de/wp-content/uploads/2022/08/RA2022_Erste_Ergebnisse_Broschuere_DE.pdf.}

^{198 - FUR 2022, cf. endnote no. 197}

^{199 - BSH – Bundesamt für Seeschifffahrt und Hydrographie (Hg.) 2018: Fact Sheet – Temperaturen Nord- und Ostsee. 2 pp.}

^{200 - infas – Institut für angewandte Sozialwissenschaft GmbH 2022: Tabellenband – Zusatzbefragung im Rahmen der Umweltbewusstseinsstudie 2020. Themenbereich: Klimaanpassung. Bonn, 39 pp. https://www.umweltbundesamt.de/sites/default/files/medien/2378/dokumente/tabellenband_ubs_zusatzbefragung_sept_2021_klimaanpassung.pdf.}

TOU-I-1: Coastal bathing temperatures | Umweltbundesamt