🇵🇱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 2,499 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; mountainous regions remain below 0°C year-round at highest elevations. 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 averages −3°C in January and 19°C in July with 550 mm annual precipitation distributed fairly evenly. Kraków records −3°C in January and 19°C in July with 680 mm. Wrocław (hottest major city) reaches −1°C in January and 19°C in July with 580 mm. Gdańsk on the Baltic coast registers −1°C in January and 18°C in July with 530 mm plus maritime moderation. Poznań averages −2°C in January and 19°C in July with 520 mm.

Białystok (northeastern continental influence) drops to −5°C in January and 18°C in July with 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, 300-600 mm rainfall, 56 Polish deaths, $2.3-3.5 billion damage) 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 experiences recurring droughts — multi-year droughts 2018-2022 affected eastern Polish agriculture, the August 2015 heatwave, declining Tatra snowpack, the August 2022 Oder River low-water event affecting fish populations, 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 warmest July averages occur in Tarnów, around 23.8°C, while Białystok records the coldest January nights 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.