🇵🇱Poland

Poland (approximately 312,696 km²) extends across the North European Plain from 49°–55°N, bordered by the Baltic Sea (770 km coastline) to the north, the Sudetes and Carpathian Mountains (highest peak Rysy at 2,500 m) to the south, and spanning diverse topography from coastal plains through lake districts to mountain ranges.

The country features temperate continental climate (Köppen Cfb/Dfb) with four distinct seasons, though climate zones vary considerably: maritime influences moderate the Baltic coast and western regions, while eastern Poland experiences greater continental extremes with hotter summers and colder winters.

Mean annual temperatures range from 6°C in the northeast to 10°C in the southwest; on the highest mountain peaks the annual mean is below 0°C. Two major river systems dominate hydrology: the Vistula (1,047 km, draining eastern Poland) and the Oder (854 km, draining the west), both flowing northward into the Baltic Sea.

Warsaw sees January highs of about 1°C with nights near −4°C and July highs of 25°C with 550 mm annual precipitation. Kraków has January highs of 2°C with nights near −5°C and July highs of 25°C with 670 mm. Wrocław (hottest major city) reaches January highs of 3°C with nights near −3°C and July highs of 26°C with 540 mm. Gdańsk on the Baltic coast has January highs of 2°C with nights near −3°C and July highs of 23°C with 570 mm plus maritime moderation. Poznań has January highs of 2°C with nights near −3°C and July highs of 25°C with 520 mm.

Białystok (northeastern continental influence) drops to −5°C on January nights, with July highs of 24°C and 590 mm. The Tatra Mountains receive over 1,300 mm annually with heavy winter snowfall. Poland experiences recurring major flooding: the September 2024 Central European floods (Storm Boris) dropped over 400 mm in three days across southwestern regions, killing 9 people, affecting Głuchołazy, Nysa, Kłodzko, and Stronie Śląskie; the 1997 Millennium Flood (July, locally over 500 mm of rainfall, 56 Polish deaths) struck the Oder basin including Wrocław, Opole, and Racibórz; the May-June 2010 Vistula floods (25 deaths, €2.5 billion damage) affected Kraków, Sandomierz, and Płock.

Poland also faces recurring droughts and other climate shifts: declining snow cover, the August 2022 Oder River fish kill amid drought-lowered water levels, and Baltic Sea levels rising 13–15 cm above 1950 baselines.

Our archive covers 47 Polish cities with daily ERA5 reanalysis data going back to 1940. The hottest July afternoons are in Tarnów, with average highs around 23.8°C, while Białystok has the coldest January nights, with average lows near −6.6°C. Comparing the last decade against the 1940–1970 baseline, mean temperatures across these cities have risen by about 2.3°C.