The Met Office has issued a rare red weather warning for extreme heat covering parts of southern and central England and Wales, active from 9am on Wednesday 25 June until 9pm on Thursday 26 June, with temperatures forecast to reach as high as 40°C. Alongside this, the UK Health Security Agency has issued a red heat-health alert for six regions of England from 1am on Wednesday 25 June until 11pm on Thursday 25 June. Sheffield and South Yorkshire fall under an amber alert, but residents should treat this week’s conditions with the same seriousness.
If you are in an affected area, stay indoors during peak hours, check on elderly neighbours now, and keep essential supplies and a charged phone to hand.
What Is Today’s Red Weather Warning?
The Met Office red warning for extreme heat is the agency’s highest tier of alert, reserved for conditions that pose a risk to life across the entire population, not only those in vulnerable groups. It signals that dangerous weather is expected and immediate action is required.
Today’s red weather warning covers the Midlands, south-east Wales, and southern England, taking effect at 9am on Wednesday 25 June and remaining active until 9pm on Thursday 26 June. The warning area includes major cities such as Birmingham, London, Salisbury, and Swansea, extending as far north as Lincoln and Stoke-on-Trent.
The Met Office forecasts temperatures climbing to 40°C, which would break the all-time June record of 35.6°C set in Southampton in 1976. This warning sits above amber, which signals widespread impacts are probable, and well above yellow, which indicates localised disruption. A red warning means those impacts are near-certain and severe enough to affect critical national infrastructure.
The official advice under a red warning is unambiguous: this is not weather to push through. Adjust plans, avoid unnecessary travel, and take active steps to keep cool.
Sheffield and South Yorkshire: What This Means Locally
Sheffield sits within the Yorkshire and the Humber region, which the UKHSA has placed under an amber heat-health alert from 1am on Wednesday until 11pm on Thursday. The Met Office 7-day forecast for Sheffield shows temperatures reaching 35°C on Wednesday and 36°C on Thursday, with heat feeling like 36°C at peak. Those are among the highest readings South Yorkshire residents are likely to have experienced.
Travel and Roads
Northern Rail and TransPennine Express are expected to implement speed restrictions across South Yorkshire rail lines due to track buckling risk at extreme temperatures. Tram Supertram services on the Sheffield network may face service alterations, and drivers on the M1, M18, and A57 should anticipate tarmac surface issues and increased breakdowns in the heat. Highways England typically advises drivers to carry water, ensure coolant levels are correct, and check tyre pressures before extended journeys during heat events.
Schools and Healthcare Pressure
The NASUWT teaching union has confirmed that under a red extreme heat alert, school leadership must carry out an immediate supplementary risk assessment, with full or partial site closures a legitimate outcome. Sheffield schools currently under amber should already be conducting that review, given the Met Office forecast trajectory. The NHS and UKHSA have warned that significantly increased demand on all health and social care services is expected, alongside a direct risk to the ability of staff to deliver care in hot indoor environments.
Sheffield Teaching Hospitals NHS Foundation Trust, Rotherham NHS Foundation Trust, and Doncaster and Basingstoke NHS Trust are all within the affected amber zone and should expect elevated A&E presentations for heat exhaustion, dehydration, and heatstroke this week.
Outdoor Events and Vulnerable Residents
Any outdoor public events scheduled in Sheffield or Rotherham for Wednesday or Thursday should be reviewed urgently by organisers. South Yorkshire’s ageing population, particularly residents in upstairs flats in Hillsborough, Burngreave, and Darnall, face the greatest risk, as overnight temperatures in urban areas are expected to struggle below 20°C, creating what meteorologists describe as “tropical nights”.
Which UK Areas Are Affected?
The red weather warning and UKHSA red heat-health alert cover the following areas:
Red Weather Warning (Met Office) — Wednesday 9am to Thursday 9pm:
- East Midlands (including Nottingham, Leicester, Derby)
- West Midlands (including Birmingham, Coventry, Wolverhampton)
- South East England (including London, Brighton, Kent, Oxford)
- South West England (including Bristol, Exeter, Bournemouth)
- South-east Wales (including Swansea and Cardiff)
UKHSA Red Heat-Health Alert — Wednesday 1am to Thursday 11pm:
- East of England
- East Midlands
- West Midlands
- South East
- South West
- London
UKHSA Amber Heat-Health Alert — same period:
- North West England
- North East England
- Yorkshire and the Humber (including Sheffield, Leeds, Bradford)
Wales: The Met Office red weather warning explicitly covers south-east Wales, making it one of the most acutely affected areas during the peak of Wednesday and Thursday. North and mid-Wales sit under amber.
Scotland and Northern Ireland: No red weather warnings are in force. These areas remain at yellow or unaffected, though the wider amber extreme heat warning for England and Wales does not extend to these nations.
What the Met Office and UKHSA Are Saying
The Met Office issued the red extreme heat warning on 22 June, citing growing confidence that temperatures will break June records and approach or reach 40°C in southern and central England. Chief forecasters noted the warning covers a period when “extraordinarily hot and humid weather poses a threat to a substantial portion of the UK”.
The agency has also warned of considerable disruption to transport, energy resources, and the potential for widespread damage to buildings and infrastructure. Power grid stress is a particular concern during prolonged extreme heat, given increased demand from cooling systems.
The UKHSA has been equally direct. Its red heat-health alert, the highest level it can issue, states that severe impacts are expected across health and social care services, including an “increased risk to life across the whole population” and significantly increased demand that could compromise the workforce’s ability to deliver care. Critical infrastructure failures, including generator outages and power disruptions, are listed as credible risks.
The government advises calling 999 immediately if someone shows signs of heatstroke, such as confusion, loss of consciousness, or failure to cool down within 30 minutes despite intervention.
Safety Advice for Sheffield and UK Residents
Acting on official guidance this week is not optional, it is life-protecting. Follow these steps now:
- Stay indoors between 11am and 3pm, when UV radiation and ambient heat peak
- Drink water regularly even without thirst; avoid alcohol and caffeine, which accelerate dehydration
- Close sun-facing curtains and blinds during the day and open windows only after temperatures drop after dark
- Avoid unnecessary travel on Wednesday and Thursday, particularly road and rail journeys at peak heat
- Check on elderly or isolated neighbours today and again on Wednesday morning
- Keep essential supplies ready: bottled water, a fan, light food, and any prescription medication
- Charge your phone fully and download offline maps in case network infrastructure is affected
- Know heatstroke signs: heavy sweating, dizziness, rapid heartbeat, nausea; move the person to shade, cool them and call 999 if there is no improvement within 30 minutes
- Monitor the Met Office website and UKHSA dashboard for live warning updates
Water safety is a separate urgent concern. Coastal areas, lakes, and rivers, including Sheffield’s Damflask Reservoir, Rother Valley Country Park, and Ladybower, attract large crowds during heatwaves. Cold water shock is a genuine risk regardless of air temperature.
Why This Weather Event Is Significant
This is not a routine British summer. The Met Office’s red weather warning for extreme heat has been issued only a handful of times, and forecasters have explicitly described this week as potentially record-breaking for June. Temperatures of 38°C to 40°C in central England would place this event in the same category as the devastating July 2022 heatwave, during which the UK recorded its all-time high of 40.3°C.
The climate context is clear. Scientists at the Met Office and internationally have consistently linked the increasing frequency and intensity of extreme heat events in the UK to human-driven climate change. Events that were once in 50-year occurrences are becoming regular summer features.
Infrastructure built for a temperate British climate, including Victorian rail lines, older social housing stock, NHS buildings without adequate ventilation, and road surfaces designed for cool conditions, faces enormous stress during these episodes. The energy grid, under pressure from widespread cooling demand, is a further concern flagged by UKHSA. Beyond infrastructure, the health toll is real: heat mortality among the over-65 population rises sharply during sustained events, and UKHSA has acknowledged “increased mortality rates” as an expected consequence of this alert level.
What Happens Next
Today, Monday 22 June, an amber extreme heat warning is active for much of southern and central England, with conditions warming steadily. Tuesday will see temperatures reaching 34 to 35°C in London and the South East before the peak arrives.
The critical period begins on Wednesday morning, when the red weather warning activates at 9am. The hottest conditions are forecast for Wednesday afternoon into Thursday, when thermometers in central London and the Midlands could touch 40°C. Overnight temperatures on Tuesday and Wednesday night will remain above 20°C in cities, with Sheffield likely staying above 18°C, disrupting sleep and raising sustained heat stress.
The red warning lifts at 9pm on Thursday 26 June. Forecasters currently expect a breakdown in the heat by Friday as Atlantic pressure builds and cloud increases from the west, though showers may accompany the cooler air. Residents in Sheffield and South Yorkshire should expect temperatures to fall back toward the mid-20s by the weekend.
Met Office forecasters continue to monitor the situation and may extend or upgrade warnings if the heat exceeds current projections. The UKHSA dashboard at ukhsa-dashboard.data.gov.uk is updated multiple times daily and remains the definitive source for regional health alert status.
Read More: UK Weather Today: Sheffield to Feel Impact as Met Office Warns 35C Heatwave Could Break June Record
