Will the UK Need Air Conditioning? Heatwaves and Heat Health Alerts (2026)

Will the UK need air conditioning? About 4% of homes in England already use it, and more will need it, though not every home and not before the cheaper fixes. In June 2026 England had only its second red heat health alert, summer 2026 was provisionally the UK’s warmest on record, and the Climate Change Committee (CCC) says around 22% of the UK’s homes would need active cooling, such as air conditioning, at 2°C of global warming. We’re based in Christchurch, so alongside the national picture, here’s what the figures say for Dorset.

What a heat health alert means, colour by colour

Heat health alerts come from the UK Health Security Agency (UKHSA), working with the Met Office. The current, impact-based system launched on 1 June 2023 and covers England. Each colour weighs how serious the health impacts could be against how likely they are, with likelihood rated from below 30% to above 90%. The core season runs from 1 June to 30 September, though alerts can be issued outside it.

Colour	What UKHSA says it means
Green	No alert: conditions are likely to have minimal impact on health
Yellow	Heat unlikely to affect most people, but particularly vulnerable people, such as older people with several health conditions, are likely to struggle
Amber	Impacts likely across the whole health service, with potential for the whole population to be at risk
Red	Significant risk to life for even the healthy population

The alerts are aimed mainly at health and social care staff and responders. Anyone can register for them by region, and the current status is shown on the UKHSA Data Dashboard. The Met Office’s extreme heat warnings are separate, come only in amber and red, and are written for the public too.

The temperatures behind each alert

There’s no automatic trigger, but UKHSA’s user guide (version 2.2, April 2025) lists the forecast temperatures it uses as a decision-making aid. Outside London, every region, Dorset’s included, uses the same figures:

Impact level	Daytime maximum, outside London	Daytime maximum, London	Rise in deaths above expected levels
Very low	Below 27.0°C	Below 28.0°C	Not applicable
Low	27.0 to 29.9°C	28.0 to 31.9°C	10%
Medium	30.0 to 37.9°C	32.0 to 39.9°C	20%
High	38.0°C and above	40.0°C and above	50%

Warm nights count too: a night among the warmest 5% of summer nights adds to the assessment.

Why yellow alerts still matter

UKHSA’s own figures show why a yellow alert shouldn’t be shrugged off. Summer 2023 brought five heat episodes, two amber alerts and three yellow, and over 2,000 heat-associated deaths. The highest daily average, 129 deaths a day, came during a short yellow alert from 10 to 12 August 2023, more than in either amber spell.

The NHS lists those most at risk, including people aged 65 and over, children aged 5 and under, people who are pregnant or have serious long-term conditions, and people who live alone. At the 2021 Census, 29.6% of residents in the Dorset Council area and 21.6% in Bournemouth, Christchurch and Poole were 65 or over, against 18.4% across England. UKHSA’s 2025 report found the highest heat-associated death rates among people aged 85 and over.

Heat health alerts in Dorset and the South West

Alerts are issued by region, and Dorset falls in South West England. For summer 2025, UKHSA’s mortality report records amber alerts in every region during the June heat episode, in place until 23 June, then amber for the South West from 27 June to 2 July and from 11 to 15 July, and a yellow on 12 August.

In June 2026 the South West was one of the regions under the red alert, from 24 to 26 June.

The Met Office’s own heatwave test is separate: at least three days in a row at or above a county threshold. On its threshold map, Dorset’s is 26°C.

Good to know A yellow alert can still be deadly: in August 2023 a short yellow spell had the highest average daily toll of any alert that summer.

How many people die in UK heatwaves?

UKHSA estimates heat-associated deaths in England each summer:

Summer	Heat-associated deaths in England
2022	2,985, the record
2023	Over 2,000, across five heat episodes
2024	1,311
2025	1,504, across five heat episodes
2026, May and June only	2,877 (interim)

Of 2026’s deaths so far, 2,124 are linked to the eight-day June heatwave that brought the red alert, and final figures are due in early 2027. The CCC puts heat-related excess deaths in heatwave periods across the UK at 1,400 to 3,000 a year now, rising to 3,000 to 10,000 a year by 2050 at 2°C of global warming without further adaptation.

Is the UK getting hotter?

Yes. The UK’s highest temperature on record is 40.3°C, at Coningsby in Lincolnshire on 19 July 2022. The Met Office’s State of the UK Climate report on 2025, published in July 2026, found 2025 was the warmest year in a UK series running from 1884, that 2016 to 2025 was 1.33°C warmer than 1961 to 1990, and that days over 30°C in Greater London had more than quadrupled. Summer 2026 then provisionally beat 2025’s record, at 16.5°C against 16.1°C, and the Met Office says human-induced climate change made it around 130 times more likely.

Its UKCP18 projections, under a high-emissions scenario, put summers 0.9°C to 5.4°C warmer by 2070 than in 1981 to 2000, and hot spells over 30°C for two or more days running, about once every four years over the southern UK then, at about four a year. That’s one scenario, not a forecast.

Dorset summers: mostly warm, occasionally extreme

At the Met Office climate station at Hurn, north of Bournemouth and Christchurch, July days averaged a high of 22.2°C over 1991 to 2020, and July nights a low of 12.1°C: well short of Dorset’s 26°C heatwave threshold and the 27°C where UKHSA’s low-impact band begins. But averages creep up, and single months can stray a long way:

Hurn, July	Average daily maximum
1961 to 1990 average	21.4°C
1991 to 2020 average	22.2°C
July 2022	24.7°C
July 2025	24.8°C
July 2026 (provisional)	28.0°C

July 2026’s provisional 28.0°C is the highest monthly average maximum in Hurn’s record, which starts in 1957, with just 0.6 mm of rain. The Met Office called it Southern England’s warmest July on record for mean temperature, with Dorset 3.5°C above average.

How to keep cool in a heatwave

Before you spend anything, the NHS advice on how to keep cool in a heatwave costs little:

• close windows, curtains and blinds during the day, and open them at night once it’s cooler outside;
• use electric fans, which can help while the temperature is below 35°C;
• have cold food and drinks, drink extra fluids, and avoid alcohol, caffeine and hot drinks;
• take a cool shower, or put cool water on your skin or clothes;
• if you have to go out, stay in the shade, especially between 11am and 3pm;
• check room temperatures where people at higher risk live and sleep, and check on them.

Heat exhaustion doesn’t usually need emergency help if the person can cool down within 30 minutes, the NHS says, but heatstroke is a medical emergency: call 999 if they’re still unwell after 30 minutes of resting somewhere cool, being cooled and drinking fluids, or show signs such as a seizure or loss of consciousness.

Good to know Closing curtains and blinds by day and opening windows at night costs little, and fans help while it’s below 35°C.

What the Climate Change Committee says about air conditioning

In A Well-Adapted UK (May 2026), the CCC says 92% of existing homes would overheat at 2°C of global warming in 2050 without further adaptation, with smaller homes, conversions and top-floor flats facing higher exposure. Natural shading and other low-cost passive measures may be enough in some parts of the country, but “we need to plan for more active cooling (such as air conditioning)”, especially in existing homes, and around 22% of the UK’s housing stock would require it. For the most vulnerable urban households, it suggests at least one cool room, and it expects that “most households will invest in cooling themselves”.

Few have so far: a University of Reading study of English Housing Survey answers from 2023 to 2024 found 4.3% of homes in England use air conditioning.

When air conditioning makes sense

Air conditioning earns its place in rooms that still overheat after shading and night-time airing. The Energy Saving Trust gives the same order: passive cooling first, then speak to an installer if your home still overheats. Typically, that means:

• top-floor rooms, given the CCC’s warning about top-floor flats (see our guide to cooling a loft conversion);
• bedrooms that stay warm into the night, where the quietest units for sleeping matter;
• one cool room for an older or vulnerable relative.

The CCC’s citizens’ panel expected people to buy portable units as “quick fixes”. A split system, with its compressor outside, is the longer-term answer, and it’s what our air conditioning installation work from Christchurch covers. In England since 29 May 2025, permitted development has covered an air-to-air unit that isn’t used solely for cooling and meets noise, size and siting conditions.

Good to know Air conditioning makes most sense in the rooms that still overheat after shading, night-time airing and fans.

A split system can heat in winter too

Many split systems run both ways. The Energy Saving Trust notes that “many systems can also provide heating”, and the CCC suggests support for heat pumps capable of cooling as well as heating. Both makes we fit do: Daikin’s Perfera wall units heat, cool and purify the air, and the Bosch Climate 3200i gives on-demand heating and cooling for individual rooms. Air-to-air systems don’t usually heat your water, so that stays with your current system.

Heating also counts for planning, as permitted development excludes a unit used solely for cooling. Whether it’s air conditioning we fit in Poole or heating-and-cooling systems across the rest of Dorset, we work out the right unit for each room at a free survey.

So, will the UK need air conditioning?

Some of it will. The average Dorset summer day stays well below the temperatures behind a heat health alert, and the NHS steps go a long way. But summers 2025 and 2026 each set a new UK record, the second provisionally, and the CCC expects more than one home in five to need active cooling at 2°C of warming. If a room in your home overheats whenever a heat health alert goes out, book a free survey and our team will look at whether a split system, for summer and winter, is worth it.