22/06/2026
Takeaway: Extreme heat exposes structural weaknesses in the Cymru school estate, and employers must treat Red Warnings as serious health and safety events.
This week’s Red Extreme Heat Warning for parts of Cymru is a stark reminder of a long‑standing issue in our education system: many school buildings are simply not designed for modern climate conditions.
Across Cymru, staff are reporting classrooms where:
• Windows open only a few centimetres, providing no meaningful airflow
• Ventilation is inadequate, allowing CO₂ levels to rise rapidly
• Internal temperatures exceed safe working limits, especially in upper‑floor or south‑facing rooms
When the Met Office issues a Red Warning, it signals a high likelihood of serious health impacts. These warnings are exceptionally rare — and they demand a proportionate response from employers.
Extreme heat affects:
• Cognitive performance
• Behaviour and emotional regulation
• Staff wellbeing and fatigue
• The safety of vulnerable learners
Employers must recognise that this is not a routine weather event. It is a health and safety risk that requires adaptation and a willingness to prioritise wellbeing over rigid routine.
This week’s temperatures should be a wake‑up call.
The Cymru school estate needs urgent investment in ventilation, cooling, and climate‑resilient design. Until then, leadership teams must take these warnings seriously and act decisively to protect staff and pupils.
Although there is no legal maximum temperature in the UK, the World Health Organization recommends a maximum temperature of 24°C. UK legislation requires working temperatures to be reasonable, and employers have a duty to take any action that is reasonably practicable to achieve this. Further details are given in the link to our website below.
If the school does not resolve the problem, contact the NASUWT Cymru for advice.
The NASUWT offers information and guidance on excessive temperatures in schools, including regulation 7 of the Approved Code of Practice on Workplace Regulations 2013 which deals specifically with the temperature in indoor workplaces.
