As temperatures soar across the UK, consumer group Which? has endorsed a 'sunset rule' to help keep homes comfortable. The method involves keeping windows closed during the hottest part of the day and opening them only after sunset when the outside air is cooler.
Met Office Forecast
The Met Office has said temperatures are expected to decline toward the end of the week. On Wednesday, Met Office Chief Forecaster Paul Gundersen said: "Today will see the highest temperatures of the week, with some locations in eastern England expected to reach 35°C. However, a marked change of weather type is due from the end of the week, bringing more unsettled conditions to the northwest of the UK and temperatures closer to the seasonal average."
He added: "Scotland and Northern Ireland will see cloudier conditions with outbreaks of showery rain, although here too brighter spells are possible. A temperature value of 35°C today will be the seventh day of 2026 when the UK has recorded a value of 35°C or higher. Prior to this year, the record was five days of 35°C or above in a single year set in 1976."
Which? Advice
Which? shared the tip in a TikTok video this week. The caption said: "Another week, another heat wave. With temps set to reach 35 degrees in some parts of the UK on Wednesday, here's your friendly reminder: keep the windows shut during the day! Open them only at sunset when it’s cooler outside. And remember, like a greenhouse, sunlight through glass can really raise indoor temperatures. Use curtains, blinds, or shutters to stay comfortable all day long!"
The team member explained: "Windows and blinds open during the night. Windows and blinds shut during the day. Windows let hot air out in the night. Windows let hot air in in the day."
British Red Cross Tips
The British Red Cross offers similar guidance. The charity says: "Homes in the UK are traditionally built to retain heat, helping us stay warm during colder months. But this works against us during heatwaves and makes homes harder to cool down."
The British Red Cross website advises: "Opening a window doesn't always mean you're cooling your home. In fact, if the air outside is warmer you could risk making it worse. During the hottest parts of the day, it's best to close windows to keep the warmer air out. Check the forecast to gauge when temperatures are starting to rise. Wait until the cooler times of the day to open windows. When they are open, you can create a breeze in your home by opening different windows to help air circulate."
