Travel and health warnings have gone out as temperatures are predicted to hit 35C (95F) today (Wednesday), making a level 3 heatwave alert likely.
Asthma and hay fever sufferers are being warned as Met Office are forecasting a high or very-high pollen count over the coming days, with possible thunderstorms in the Midlands, southern Scotland, and northern England and Wales.
The level 3 alert - one below a national emergency - is triggered when the Met Office confirms a 90% chance of heatwave conditions.
When the alert is issued, social and healthcare services must mobilise community and voluntary support for high-risk groups and media alerts about keeping cool are issued.
Professor Paul Cosford, director for health protection and medical director at Public Health England (PHE) said: “Local authorities and the NHS should now be familiar with PHE’s Heatwave Plan, which aims to reduce health risks related to heat. Those looking after schoolchildren or pre-schoolers during the hot spell should ensure they’ve read the guidance in the plan, which includes specific advice on how to keep children safe on very hot days.
“While hot weather is enjoyable for most people and uncomfortable for some, sadly experience tells us that exposure to excessive heat can kill, with most cases of illness and death caused by heart and lung disease. Because we are not used to these very hot temperatures in England, it’s important that local plans are in place to reduce the impact of harm from very hot weather.”
Dr Angie Bone, head of extreme events at PHE, said the heat could be dangerous for older people, young children and those with serious illnesses, and urged employers to be flexible.
She said: “During very hot weather, pregnant women and people who have chronic illnesses, including cardiovascular, respiratory, renal conditions, diabetes or Parkinson’s disease, may experience discomfort if indoor temperatures are particularly hot and in using public transport.
“Employers should ensure indoor areas are kept cool and consider allowing these individuals to travel to or from their place of work during cooler, or less busy times of the day. For those working or exercising outdoors, strenuous physical exertion during the hottest part of the day should be kept to a minimum.”
The heatwave is being caused by a warm front and tropical continental air mass from Europe pushing across the country, bringing high temperatures, humidity and possibly Saharan sand.
Vicky Barber from the British Lung Foundation Helpline said: “During hot weather, the air we breathe has lower moisture levels than usual, which can have a drying effect on our airways. As a result, people with respiratory conditions such as COPD (chronic obstructive pulmonary disease) or severe asthma may find it harder to breathe, feel more tired, or find their lungs feeling heavy or tight.”
She recommended that people with lung conditions avoid going outside at midday, wear loose clothing and drink plenty of water.