Heat changes matches quickly.
For Scotland, that matters. Clarke’s side are usually most effective when they are organised, aggressive without the ball and able to sustain concentration for long spells. Even mid-20s temperatures can become a problem when humidity, travel and tournament stress are added. The report says pressure is also growing on to strengthen heat-protection protocols before the competition begins.
Scottish football has seen enough examples to treat this seriously.
The report points back to 1994, when World Cup conditions in the United States became a major talking point, and to Graeme Souness recalling severe physical strain at Mexico 1986. It also cites more recent club cases involving Hearts, Celtic, St Johnstone and Motherwell, where extreme heat was said to affect performance and recovery.
That history matters because it shows a pattern: Scottish teams are not uniquely fragile, but they are often moving into climates very different from their domestic rhythm. The margin between controlled football and survival mode can disappear fast.
Clarke and his staff cannot control the weather, but they can shape the response.
That is especially relevant against opponents like Morocco and Brazil, where long defensive phases can drain legs and concentration.
Scotland still have time to prepare, and that may prove as important as any tactical tweak. The next storyline to watch is whether tournament organisers adjust welfare measures - and whether Scotland arrive ready not just for the occasion, but for the climate.