Summer 2025 by many has been perceived as cool and wet. Sadly, when such observations were shared in public, they fuelled claims global warming is a hoax, despite numerous figures giving lie to flat-earth believers and other wackos. In fact, in Warsaw this summer was thermally normal and dry (benchmark period: 1991 – 2020).
June 2025 with mean temperature of +18.5C and total precipitation of 47.7 millimetres was slightly warmer and drier than long-term average (respectively: +17.7C and 63.9 millimetres).
July 2025 with mean temperature of ++20.0C and total precipitation of 53.8 millimetres was normal and markedly drier than long-term average (respectively: +19.7C and 82.2 millimetres).
August 2025 with mean temperature of +19.3C and total precipitation of 9.2 millimetres was slightly warmer and extremely dry in comparison to long-term average (respectively: +17.7C and 60.6 millimetres).
The first week of September brought temperatures a few degrees above long-term averages and little rainfall. The summer-like weather is foreseen to continue at least for the next two weeks.
The total number of hot days (defined as those with maximum temperature above +30C) has reached 11 so far (the last one on Friday, 5 September) and in line with weather forecasts it stands a little chance to still go up. It is conceivable, as in the past the capital of Poland saw three incidences of heat in second decades of September in Warsaw: 14 September 1951, 11 September 2012 and 13 September 2023. On top we have had so far 8 days with highs between +28C and +30C, which formally do not meet the definition of a "hot day".
Not everyone is fond of such weather. I belong to those whose bodies don't feel well in high summer and hence I have highly appreciated moderate weather, milder than in recent years.
Hot summers in Poland are still colder than what residents of southern Europe had to endure decades ago, when air-conditioning was not widespread. Since central heating was also a missing installation in most dwellings, walls were thick and windows were tiny. Window shutters gave shelter both from the heat and the cold. Roofed terraces did not let sunrays reach windows in when the sun was shining high. The price to pay were dark interiors.
I last recalled how old-style architecture protected from heat, when I entered a several-century old monastery in Święty Krzyż. With +29C and full sunshine outside, the edifice gave great shelter from heat, despite no air-condition inside.
On Friday I strolled around the centre of Warsaw and stared at modern skyscrapers. They all had walls made entirely from glass, with each storey having windows from floor to ceiling. I realise window panes these days need to meet stringent energy efficiency requirements, but glass will never be as energy-efficient as a 40-centimetre-thick brick wall. All those modern buildings can boast of fancy eco-certificates, while their architecture boosts their energy demand. The same applies to modern premium properties, with large windows being a housing equivalent of SUVs in motoring.
No energy is fully green. Generating electricity from solar panels involves carbon footprint 95% lower than from burning black coal, while for wind turbines it is 99% lower. The calculations take into account total life cycle of specific installations (source: ChatGPT).
In the office building where I work, radiators blowing in hot air and air-conditioning blowing in cold air were working at full blast all summer round. No matter how green the energy is, such waste of energy in a building which boasts of being energy-efficient is unacceptable. Same as a defunct fire alarm which has failed to inform of two small fires in the underground garage this year...
Old, energy-inefficient buildings are torn down and new, energy-efficient ones are constructed on the same plots. Has anyone calculated how many years of lower energy usage it takes to make up for carbon footprint in the demolition and subsequent construction? ChatGPT needed 4 minutes to come up with an answer: 30 years for a typical energy-efficient building, 15 years for an ultra-energy-efficient building. I have not verified it, but if it is true, business and money matters much more than actual care for environment. Much better for the planet would be to modernise existing buildings.
No matter how green the electricity that powers air-conditioning is, detrimental effects of prevalent aircon in city centres persist. Masses if hot air are blown outside several buildings and along with excessive concrete areas, exacerbate the urban heat island effect, making living conditions in city centres unbearable, especially for elderly residents.
