The new heat health alerts come as a second heatwave of 2025 is expected in parts of the UK after the first saw this year’s hottest day recorded – 33.2C in Charlwood, Surrey on 21 June.

Humidity is set to soar on Friday as a warm airmass associated with the recent extreme heatwave in the USA makes its way across the Atlantic.

While temperatures will be warm for most of England, rain and showers are forecast in the North West.

However the mercury is set rocket over the weekend for swathges of England thanks to a ridge of high pressure over Europe.

On Saturday temperatures will more widely cross ‘heatwave thresholds’ before getting more intense into Monday, which is likely to be the heat peak.

In East Anglia and south-east England temperatures are likely to reach 33-34C, challenging or surpassing that highest temperature of 2025.

The UKHSA alert system works in conjunction with the Met Office but has a focus on health risks in a bid to provide early warnings for health and government services.

There are four levels of warning – green, yellow, amber and red – an amber warning means the whole health service is likely to be affected by the hot weather.

Among examples given by UKHSA are difficulties managing medicines, the ability of the workforce to deliver services and internal temperatures in care settings exceeding the recommended thresholds.

The agency also refers to a possible rise in deaths – particularly among those aged 65 or over or with health conditions – as well as health risks to the wider population.

There are lots of summer events that will be affected by the heat. It’s likely to be the hottest start to Wimbledon, surpassing the record of 29.3C (measured at Kew) from 2001.

Temperatures will get close to the Glastonbury record of 31.2C (measured at Rodney Stoke) recorded in 2017.

The hot weather is likely to make the beginning of next week’s Wimbledon tennis championships a real scorcher for fans and players alike.

BBC lead weather presenter Chris Fawkes warns of next week: “The heat will get even more intense on Monday, which is likely to be the peak of the heatwave.

“In East Anglia and south-east England temperatures are likely to reach 33-34C, challenging or surpassing the highest temperature of 2025.

“This is extreme heat and isn’t far away from the June record which stands at 35.6C (96F), recorded at Southampton during the infamous summer of 1976.

“There’s more uncertainty in the forecast for Tuesday onwards. Many computer models suggest cooler and fresher air arrives from the west, but it’s not inconceivable that the hot weather clings on for another day or so in the east.”

No heatwave is expected in Scotland and Northern Ireland with temperatures more generally staying into the low 20Cs.

There will be some warm spells of sunshine around, but also the prospect of some areas of rain – for example rain could be heavy on Monday.

Heatwaves can cause problems for our infrastructure, such as trains running at reduced speeds due to the risk of train tracks expanding and buckling in the heat.

We also see more heat-related health problems which can lead to an increase in excess deaths in those with underlying health conditions.

Heat-health alerts are issued to warn health providers of the risk of a heat causing adverse impacts to the health and wellbeing of the population.

Adrian Champion, Head of Climate Analytics UK & EMEA at insurance providers Aon, said businesses are not fully ready to deal with the effects of high temperatires.

He said: “The UK simply isn’t prepared for this heat, which is why disruption can feel so widespread.

“Air conditioning is less common here than in countries with hotter climates, and where it is installed, systems aren’t necessarily designed to cope with such high temperatures. During previous heatwaves we’ve seen an uplift in claims relating to disruptions caused by air con failures.

“It’s also important not to overlook the impact that this heat can have on employees. Transport disruptions, poor sleep and increased illness can all limit people’s ability to work productively.

That’s why more businesses are looking at climate modelling and scenario planning to help them to future-proof operations as heatwaves become more common.”

He went on: “Record-breaking heat could reshape the tourism and hospitality calendar. Some holiday hotspots might see their seasons become shorter as temperatures become less comfortable for visitors, while other, cooler destinations may benefit from a prolonged peak period.

“For the travel and hospitality industry, this means rethinking how they plan ahead. Airlines may need to alter the size and schedules for certain countries, while hotels and restaurants may find they need more staff at different points in the year to meet changing demand.”

What do the heat alert levels mean?

The level of alert is based on Met Office forecasts and data.

There are four levels ranging from green (least severe) to red (most severe):

Green

Green is the normal level, when advice is given on how people should prepare to respond if temperatures rise or fall.

Yellow

Yellow 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 conditions.

Amber

Amber 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 example.

Travel disruption is also likely.

Red

A red alert is the most severe.

It 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.