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How do heat and cold health alerts work?
The first yellow heat health alerts of 2025 have been alerts mean the weather poses a greater risk to vulnerable people, which may place additional pressure on health services.
How does the weather health alert system work?
The weather alert service warns the public in England when high or low temperatures could damage their system is run by the UK Health Security Agency and the Met includes both heat health and cold health alertsHeat health alerts are issued between 1 June and 30 September, and cold health alerts are published between 1 November and 30 March. As well as warning the public, the system sends guidance directly to NHS England, the government and healthcare professionals during periods of adverse are categorised according to severity and include:headline weather conditions expected in the coming daysdetails of how weather conditions will affect each regionlinks to additional information, advice and guidanceThe system was designed to help reduce illness and deaths during periods of extreme current weather-health alertsCheck the UK weather warnings in placeWhen is a heatwave 'really' a heatwave?
What do the alert levels mean?
The level of alert is based on Met Office forecasts and are four levels ranging from green (least severe) to red (most severe):GreenGreen is the normal level, when advice is given on how people should prepare to respond if temperatures rise or alerts are issued during periods of hot or cold weather that are only likely to affect those who are particularly vulnerable, for example the elderly, or those with existing health alerts are issued in situations that could potentially put the whole population at risk. The NHS may see increased demand on GPs and ambulances, for disruption is also red alert is the most is issued in situations when hot or cold weather would be a significant risk to life, even for the healthy population, and could lead to failures of critical national infrastructure, such as power outages or roads and rail lines being closed.
What does hot weather do to the body?
As the body gets hotter, blood vessels open up. This leads to lower blood pressure, and makes the heart work harder to push the blood around the can cause mild symptoms such as an itchy heat rash or swollen feet, as blood vessels become leaky.
At the same time, sweating leads to the loss of fluids and salt and, crucially, the balance between them in the body combined with the lowered blood pressure, can lead to heat exhaustion and heatstroke. Symptoms include:dizzinessnauseafaintingconfusionmuscle crampsheadachesheavy sweatingtirednessIf blood pressure drops too far, the risk of heart attacks does hot weather do to the body?What are UV levels and how can you protect yourself?How to sleep in hot weather
