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The article examines the spatial and temporal variability in selected extreme meteorological phenomena on the Polish coast of the Baltic Sea. Data from the 2001-2014 period related to a few meteorological and oceanographic elements were used to calculate indices of extreme weather events. The amount of intensive and widespread precipitation events in the 21

The aim of this research is to compare daily sunshine duration data measured using a Campbell–Stokes sunshine recorder (CS) and a CSD3 sunshine duration sensor. This was undertaken because in recent decades automatic sunshine duration sensors have been systematically replacing traditional sunshine recorder. This replacement created a problem with the data quality, and the continuity of homogeneous series. The study material consisted of the daily sunshine duration sums derived from synchronous manual and automated measurements at the Borucino station (northern Poland) for the years 2015–2021. Comparison covered the daily and monthly sums and their statistical distributions. In most cases, the daily sum recorded by the sensor CSD3 was higher than that measured by the CS. On average, higher values of sums were obtained from CSD3 for all months of the year, with the exception of June. This can be explained by the higher sensitivity threshold of the CS, as well as by the difference in height of both instruments above the station’s level. Higher daily totals recorded by the CS than by the CSD3 occurred not only in June. The cause was most likely the so-called “overburning effect”. Monthly regression equations were determined, allowing for substitution of the CS measurement results with the values recorded automatically.

The study aims to analyze the variability of the precipitation character of seasons and years at selected stations in Poland in the 21st century. The work includes six meteorological stations located in specific regions of Poland. The precipitation character of years and climatic seasons was determined using quantile classification, based on the values of 10, 30, 70, and 90% quantile of the empirical distribution of seasonal and annual precipitation. 1971-2010 precipitation data (normal period) were applied to calculate the quantiles values. In spring (MAM), the highest frequency of precipitation anomalies was recorded in Wroclaw station. In the 21st century, precipitation of only one spring period was classified as normal at this station. Seven springs were dry or very dry, and 11 were wet or very wet. The most stable seasonal precipitation in spring was observed in Suwałki station. In the years 2001-2019, the twelve spring seasons had normal rainfall. Three spring seasons in Suwałki were classified as dry or very dry and five as wet or very wet. In the summer season (JJA) Szczecin and Wroclaw recorded a high frequency of precipitation anomalies. At each of these stations, 15 summer seasons were characterized by abnormal rainfall. The frequency of rainfall anomalies in the summer season was the smallest in Suwałki, where ten seasons with abnormal rainfalls were recorded, including three seasons with low or very low rainfall and six seasons with high or very high rainfall. In the autumn season (SON), precipitation was more stable in western and central Poland, where the number of seasons with abnormal precipitation ranged between 9 in Szczecin and Wroclaw to 10 in Lodz. In Lublin, on the other hand, as many as 15 seasons with abnormal rainfall was recorded in the 21st century. In the winter season of 2001-2019, rainfall amounts of unusual nature dominated at all stations, with the frequency being higher at these located in eastern Poland. The analysis of annual sums of precipitation showed that most years were abnormal in terms of precipitation, with a higher frequency of precipitation anomalies at stations located in the eastern part of the country.

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Based on the data for the years 1981–2014 from two meteorological stations located in the central and northern part of the Żuławy Alluvial Plain, the climatic conditions for the development of tourism and recreation in this area were analyzed. The factors contributing to this type of activity are the average temperatures in the fall and winter months higher than in central Poland and lower temperatures in the summer months, a relatively small number of hot and very hot days, as well as ice and very ice days. The central part of the analyzed area is characterized by lower precipitation totals, lower relative humidity, lower number of steamy days, lower cloud cover, and a high number of days with less than 50% cloudiness than the northern part, which is favorable to tourism in this area. Due to the small number of days with snowfall and snow cover over 8 cm thick, the possibility of skiing here is limited.

The characteristics of extreme precipitation, including dominant trends, were analyzed for eight stations located on the Polish coast of the Baltic Sea for the period 1951-2010. Maximum 1-day and 5-day precipitation totals, events exceeding the 90th and 95th percentile calculated for the period 1961-1990 applied as indices enabling the assessment of the frequency of wet conditions. Annual trends were calculated using the standard linear regression method, while the fit of the model was assessed with the t-test at the 95% confidence level. Annual precipitation reaches values from 775 mm on the east coast to 683 mm on the central coast and shows positive trends on six out of eight analyzed stations, from 0.8 mm·year-1 in Swibno to 2.5 mm·year−1 in Dziwnow. The maximum 1-day precipitation totals range between 58.7 mm on the western coast to 105.0 mm on the central coast and show statistically significant trends (0.1 - 0.2 mm·year−1) in this area. There are, on average, six to seven 5-day rainfall periods recorded annually in the investigated area. The annual number of 5-day precipitation periods shows positive statistically significant trends in the central and eastern part of the South Baltic coast (0.2-0.3 per 10 years). The median of the maximum 5-day precipitation totals ranges from 21.6 mm in Swinoujscie to 78.6 mm in Ustka. Trends in changes in maximum 5-day rainfall totals reach the level of 0.1-0.2 mm·year−1 and are statistically significant in stations from Swinoujscie to Ustka and in Gdynia. The values of the 90th percentile of 1-day precipitation total are equal to 8-10 mm. Annually, there are about 16-18 days with such precipitation recorded in the area under investigation. The trends are positive (0.1-1.0 day per 10 years) on the central coast. The values of the 95th percentile of 1-day precipitation totals reach 11.5-14.0 mm. Annually, there are about 8-9 days with such precipitation recorded in the area under investigation. The trends are positive (0.3-0.4 days·10 years−1) on the western and central coast.