Influence of atmospheric blocking on solar radiation and maximum temperature in Poland during summer (1971–2023)

The study aimed to assess the impact of blocking situations (BS) on maximum air temperature (T_max) and the daily sum of solar radiation (DSSR) in Poland during the summer months (June–August) from 1971 to 2023. The results indicate an increasing trend in the frequency of BS days, particularly in southern Poland, with statistically significant upward tendencies. However, multi-decadal variability is also evident, with periods of more and less frequent BS occurrences. On average, BS occurred for 3–8 days per summer, varying by region, while in extreme years (e.g., 2015), over 20 BS days were recorded in southern Poland. During all BS days, T_max anomalies averaged up to 7 °C, and DSSR anomalies reached as high as +6 MJ·m⁻²·day⁻¹ relative to multi-year averages. A strong correlation was found between the number of BS days and T_max (r = 0.57, p < 0.001), as well as DSSR (r = 0.55, p < 0.001). Interestingly, smaller temperature anomalies were recorded near the Baltic coast, likely due to the moderating influence of sea breezes. These findings underscore the spatial variability of BS and their pivotal role in driving extreme weather conditions in Poland.