How the Exceptionally Cool May of 2025 in Poland Fits in the Country’s Global Warming Record

Episodes of pronounced cooling during transitional months can have substantial environmental and economic impacts, particularly after the onset of the growing season, when frost events lead to losses in field agriculture and orchards. The weather in Poland in May 2025 exhibited widespread negative temperature anomalies with the occurrence of late frosts. It provides a salient example of such an event under conditions of ongoing climate warming. This study quantifies the magnitude and spatial structure of temperature anomalies in Poland in May 2025 and examines the circulation conditions associated with them in the context of long-term temperature change. The analysis is based on observations from 60 synoptic stations over 1951–2025. Spatial autocorrelation diagnostics (Moran’s I, LISA), linear regression, and structural change tests were applied. May 2025 featured a mean nationwide anomaly of −2.3 °C, with local departures exceeding 2 SD. The anomaly field exhibited statistically significant positive spatial autocorrelation and distinct regional clustering of cold anomalies, particularly in eastern Poland. The cooling was associated with a predominance of cyclonic circulation and an Omega-type blocking pattern, conducive to sustained advection of cold air masses from the north. The long-term analysis confirms a statistically significant warming trend in May temperatures over 1951–2025, with no evidence of a significant structural shift in recent decades. Therefore, negative anomalies observed during the last decade, including 2025, do not represent a reversal of this trend but do not provide evidence of a reversal of the long-term warming trend. The results indicate that, in transitional months, variability in circulation regimes can intermittently mask the warming signal, and cold episodes—though less frequent—remain statistically plausible in a warming climate.