Another heatwave is on the way across parts of the UK with peak temperatures of 34C forecast as a fresh hosepipe ban has been announced.

Temperatures in the south could reach 28C on Saturday, according to the Met Office, and a week-long warning from health officials comes into force at midday in parts of the UK, saying high temperatures over the coming days could cause a greater risk to life for vulnerable people.

Meanwhile, Southern Water has issued a hosepipe pan from 12.01am on July 10 in Hampshire and on the Isle of Wight.

The Met Office said temperatures are forecast to rise to 29C on Sunday, then approach the low 30s next week before a peak of 34C on Thursday or Friday in the South East.

It is expected to be a prolonged spell of hot weather in parts of the UK, but it will not be as hot and humid as last month’s heatwave, the forecaster added.

Yellow heat health alerts have been issued by the UK Health Security Agency (UKHSA), covering the East Midlands, east, south-east and south-west of England, including London, and the West Midlands, from midday on Saturday until 8pm on July 11.

The agency said that within the warning area, minor impacts were likely across health and social care services because of the high temperatures, including increased use of healthcare services by vulnerable people and a greater risk to life to the same group.

It also warned of a potential increase in water-related incidents, including risks from cold water shock and drowning.

Met Office meteorologist Becky Mitchell said: “We have got a heatwave on the way across parts of southern England and Wales, temperatures are already quite high across the South East today, we could get 28C in London.

“Elsewhere, it’s not as hot as we have got temperatures closer to average but they will climb as we go into next week.

“The northern areas of the country will be cloudier with spells of rain at times, so there’s a north/south split.

“There will be highs of 29C tomorrow in the south. At the start of next week we will see temperatures approach the low 30s.

“The peak of the heat appears to be Thursday or Friday, 34C in the South East.

“By comparison to the heatwave we saw in June, this heatwave won’t be as hot and humid, but it will be a prolonged spell of hot weather which lasts around a week.”

Southern Water says on its website that “the warmest spring on record, followed by a record-breaking heatwave, has left river levels 25% lower than expected for this time of year”.

It adds that the River Test has lost a third of its water within the last month, “putting pressure on our ability to treat and supply your water”.

Southern Water says: “To protect local rivers, including the River Test and Itchen that supply most of your water, and to keep taps flowing, we need to introduce restrictions.

“We recognise that customers with medical needs may still need to use a hosepipe. Customers on our priority services register with medical or mobility needs, including blue badge holders and those on our WaterSure tariff, are exempt. Anything you can do to reduce or avoid hosepipe use would be greatly appreciated.”

A hosepipe ban stops customers using a hosepipe for non-essential activities, including: watering gardens, including using a sprinkler system; filling paddling pools, hot tubs, swimming pools, ponds or fountains; washing cars, patios or windows.

Southern Water says the hosepipe ban will be removed “as soon as we can”, adding “this can only happen when there’s enough water in our reservoirs, rivers and underground aquifers to meet demand”.

The UKHSA’s new alert comes after a sweltering heatwave last week, during which the Met Office issued a rare red warning for extreme heat for parts of the country and the UKHSA put red heat health alerts in place.

The UK set a provisional June temperature record of 37.7C in Lingwood in Norfolk, according to the Met Office.

It beats the previous June record for the UK of 35.6C dating back to 1976 by more than 2C.

Such records have usually been broken by only a fraction of a degree in the past.