New research reveals exact date to turn the heating on

When are we likely to turn the heating on?

Analysis of a decade of UK temperature data from the Met Office showed us when the nation’s homes really start to feel the chill.

We’ve established boiler switch-on date by tracking the point when average daily outdoor temperatures start to drop below the 15.5 °C ‘heating threshold’¹ for three consecutive days.

Table: UK ‘boiler switch-on date’ by year, 2015–2024 (Met Office HadCET)

 

In colder years, like 2015 and 2017, the switch-on date came as early as 1 September; and in milder years, such as 2023, it was delayed until 21 September.

For 2025, we’ve established the median date across the data and predicted the 8th September² as boiler switch-on date – two weeks before Autumn officially starts³.

Revealing the UK’s heating habits

With this in mind, we also conducted research via OnePoll⁴, where we surveyed 2,000 people to ask about heating habits in the summer months and the boiler switch-on.

When people do switch the heating on, 1 in 6 (17 %) said they encountered problems - from radiators that won’t heat up (33 %) to error codes or warning lights (31 %), leaks (28 %) and strange noises (24 %).

Table: Most common issues faced for those that encounter challenges at boiler switch-on

 

Yet, despite a significant number facing problems, many households still wait until the first cold snap to check their heating, risking breakdowns at the busiest time of year for repairs.

That’s why we’re urging Brits to conduct a boiler ‘test run’ well before the weather turns, to avoid joining the rush for a boiler repair in late September and October.

A short boiler run now can reveal hidden issues like low pressure, leaks or cold radiators, giving homeowners time to book a repair before engineers are at their busiest – and before a small fix becomes a bigger, more expensive problem.

The exact date to start considering your boiler ‘test run’ is 25th August – two weeks before the estimated switch-on date.

Some Brits are bucking the boiler switch-on trend

Our research also found that nearly a third of Brits (32 %) have fired up their boilers already and had the heating running this summer. Some even opted to switch on as early as the first week of June – more than three months before the rest of the UK.

More than half (54 %) said it’s simply colder than expected indoors, despite recent heatwaves.

While others did it to prevent damp or draughts (22 %), with some believing that an occasional summer run keeps the boiler in better condition (12 %).

We know British weather can’t be relied upon, but you should be able to rely on your boiler. Running it early, even for just 10 minutes, can help you spot problems and fix them before you’re relying on it every day in the colder months.

Methodology:

1. 15.5 °C base temperature is standard for calculating Heating Degree Days in the UK, as per Chartered Institution of Building Services Engineers (CIBSE) and Department for Energy Security and Net Zero (DESNZ).

2. Analysis by HomeServe using Met Office Central England Temperature (HadCET) daily mean series, 2015–2024. Switch-on date calculated as first date in September–November period with mean daily outdoor temperature below 15.5 °C for three consecutive days.

3. Official start of astronomical autumn in the Northern Hemisphere in 2025 is 22 September (autumn equinox). Source: Royal Observatory Greenwich.

4. OnePoll survey for HomeServe, July 2025. Online survey of 2,000 UK adults aged 18+, nationally representative by age, gender, and region.

5. Three-day threshold used to avoid one-off cooler days and better reflect a sustained seasonal temperature change.