The UK’s long wait for a “proper summer” has been struck another blow as a deluge of rain looks set to strike millions of Britons next month, according to new weather maps.

Huge swathes of the UK are set for a wash out on Tuesday, August 6, maps by WXCHARTS show, with major cities like Southampton, London, Birmingham and Manchester set for showers after a brutal heatwave next week.

Small patches of the British Isles will remain dry including Newcastle, though a wave of blue covers large stretches of England, Wales, Scotland and Northern Ireland. An area spanning 400 miles, stretching from the north east of England down to Cornwall, will drench towns and cities up and down the country.

Belfast also looks set to avoid the downpour, according to data collected by the weather forecast site.

It looks like London be worst hit, with an instantaneous precipitation rate chart showing the capital hit with over 5mm of rain per hour by 12am that day.

Meanwhile, Birmingham will see up to 2mm per hour, with Manchester getting less than 1mm per hour.

But for many the rain will come as a relief after the near-30C temperatures expected next week, prompting a heat-health alert to be issued by the Met Office and the UK Health Security Agency.

The agencies warn deaths due to the heat are “likely” in South East England, East Anglia and London, especially in those aged 65 and over or people with health conditions. These impacts could also be seen in younger age groups, officials warned.

Demand on remote healthcare services is likely to increase while temperatures in hospitals and care homes could exceed recommended thresholds.

The heat might also affect workers and many places indoors are likely to overheat, leading to an increased risk to “vulnerable” people who either live independently or in care settings, according to the warning.