Poland braces for violent storms and 35°C heatwave as alerts cover 15 regions

Dual threat: heat and thunderstorms

A sharp weather breakdown is unfolding across Poland this weekend. The Institute of Meteorology and Water Management (IMGW) has issued level-2 (orange) thunderstorm warnings for 10 voivodeships, mainly in the west and south, effective from Saturday afternoon. At the same time, level-1 and level-2 heat warnings cover 15 of Poland's 16 voivodeships, with only Podlaskie excepted. The simultaneous hazards prompted the Government Centre for Security (RCB) to dispatch a text alert to mobile phones across the entire country.

“Warning! Today and tomorrow (20/21.06) probable intense rainfall, strong wind and thunderstorms. Possible power outages. Avoid open spaces.”

Thunderstorm outlook and timing

The thunderstorm alerts take effect earliest at 2 p.m. on Saturday. Forecasters expect the first strong thunderstorm cells to develop during the early afternoon in a wind convergence zone over western Poland. As the day progresses, these may organise into a larger cluster, possibly a mesoscale convective system (MCS), covering much of the west by evening.

“Locally these supercells may bring very intense accompanying phenomena such as very strong wind gusts, torrential rainfall and hail up to 4–6 cm in diameter. Towards evening a larger storm cluster, or even an MCS, may form covering a significant part of the west.”

Rainfall totals of 30 to 55 mm are forecast, with wind gusts ranging from 75 to 115 km/h depending on location. Some points may see gusts of up to 100 km/h, according to TVN24. Hail of up to 4 cm is also possible. Most thunderstorm warnings expire overnight Saturday into Sunday, but in some counties they remain in force until 10 a.m. on Sunday.

Heatwave spreading across Poland

The heat warnings, issued on Friday and valid until 8 p.m. on Sunday, cover nearly all of Poland. Daytime highs are expected to reach 30–35°C, with the warmest air mass over the western regions. In Słubice, temperatures had already climbed to 28.1°C by 10 a.m. on Friday. Night-time lows will stay between 17 and 21°C, offering little relief.

Hel24

Central Poland31

Western Poland35

Hel

24 °C

Central Poland

31 °C

Western Poland

35 °C

Data from the article text

Temperature maxima vary sharply across the country. Hel is forecast to stay at a cooler 24°C, central Poland around 31°C, while the west may hit 35°C. The level-1 and level-2 warnings indicate that the heat may cause significant material losses and a threat to health and life.

Overnight shift and into Sunday

As darkness falls, the storm complex is expected to move gradually from the western parts of the country towards the centre. IMGW notes that storm cells may at times form linear structures, which strengthens wind gusts to 80–90 km/h, point-wise even to 100 km/h. The overnight hours will bring continued heavy rain and lightning to areas initially spared during the day. By Sunday morning, the thunderstorm risk will concentrate in the central belt, while heat warnings stay in place into the evening.

The combination of extreme heat and violent storms is the first such widespread event this year, according to forecasters. Authorities urge residents to avoid open spaces during storms and to prepare for possible power cuts.