BySimon King

Lead Weather Presenter

The UK is likely to experience its hottest June day on record on Tuesday with temperatures forecast to rise above 35C (95F).

Heat will build through the middle of the week, potentially reaching 40C - less than one degree Celsius below the UK's hottest ever reading.

The Met Office and UK Health Security Agency (UKHSA) have issued rare red warnings for Wednesday and Thursday in parts of the Midlands, south-east Wales and southern England with significant health and infrastructure impacts expected.

Amber warnings are also in force more widely across England and Wales as temperature rise up to the mid- to high 30s.

Heat to ramp up as week progresses

It will be a hotter day for all of us on Tuesday.

Across northern England and Wales it will get to 28 to 30C, but for the Midlands, eastern and southern England, temperatures will widely exceed 33C.

In some locations around the south Midlands towards Greater London, the mercury is expected to peak at around 36 or 37C.

This will comfortably exceed the current June temperature record of 35.6C set in 1976.

With sunnier weather across Scotland and Northern Ireland, it will also turn warmer with highs of 24 to 27C on Tuesday.

The heatwave will build further across England and Wales with a Met Office red warning coming into force at 9am Wednesday and lasting through until 9pm on Thursday.

As temperatures rise to the high 30s, the Met Office warns that the heat will impact health, infrastructure and property.

Red warnings are rare and only issued in exceptional circumstances. The last red warning for extreme heat was issued in July 2022.

This was also when the UK temperature record of 40.3C was set in Coningsby, Lincolnshire.

With forecasts suggesting we could see 40C on Wednesday or Thursday in parts of England, this record may be under threat.

UKHSA red heat health alerts, which also run through Wednesday and Thursday across the Midlands, eastern and southern England, indicate that severe impacts are expected across health and social care services, with an increased risk to life across the whole population.

Heat health alerts are intended to inform the health and social care sector and the responder community.

Amber heat health alerts have also been issued across Northern England for the same times.

High humidity to make conditions uncomfortable

High humidity will accompany the high temperatures this week.

This will make it feel more uncomfortable than the May heatwave, and indeed the historic July 2022 heatwave.

With higher humidity, our bodies cannot sweat as much and therefore retain more heat, raising body temperature.

This is when heat stress and heatstroke can become more of an issue across the population, but especially among the more vulnerable.

It will stay humid during the overnight period too - alongside potentially record-breaking warmth - as temperatures fail to fall much below 17 to 22C.

The current overnight record for the UK as a whole and for England is 22.7C, set in 1976, while for Wales it is 20.0C, from 2023.

Comparisons to June 1976

The current heatwave comes 50 years after perhaps the most memorable heatwave the UK has experienced.

There were an incredible 15 consecutive days, from 23 June to 7 July 1976, where somewhere in the UK recorded a temperature of 32.2C (90F) or higher.

Meanwhile, London Heathrow notched up 16 consecutive days of 30C (86F) or more around the same time.

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