Parts of the UK are set to heat up from this weekend, with forecasters warning that temperatures could exceed 30C.

For some areas this will mark the third heatwave of the year.

Highs could reach 33C for southern and south-eastern England with 30C possible as far north as South Yorkshire. It will be cooler in the west.

While this latest hot spell is not expected to be as intense as the record-breaking heatwave in late June, it looks set to last significantly longer, potentially into the middle of the month.

Temperatures will start to gradually rise over the weekend as high pressure from the Azores builds over the UK.

The warmest conditions are expected from Monday, with temperatures across much of England and Wales likely to peak during the middle to latter part of the week.

Several areas may meet official heatwave criteria if these temperatures persist for at least three consecutive days.

The highest temperatures will be focused across southern and eastern England, where values could exceed 30C widely.

In the north-east of England and eastern Scotland temperatures could reach the mid to high 20s.

Areas on the western side of the UK – such as Lancashire, the Lake District, western Scotland and Northern Ireland – will be exposed to an Atlantic breeze which will act like a natural air conditioner limiting temperatures to the low to mid-20s.

Currently many forecasting models show that the hot spell could persist into the middle of July – although unlikely to reach the record breaking temperatures we saw in June.

Yellow heat health alerts have been issued by the UK Health Security Agency for the East Midlands, West Midlands, east of England, London, south-east England and south-west of England, for between noon on Saturday and 20:00 BST on Saturday 11 July. They warn of a heightened risk to health, particularly for vulnerable people, due to the expected heat.

In the UK, a heatwave is defined as a period of at least three consecutive days where daily maximum temperatures meet or exceed regional thresholds. These vary by location, but are typically around 25C in much of the country and 28C in London and parts of the south-east.

During such conditions, there is an increased risk of heat-related illness, especially among older people and those with underlying health conditions.

A ridge of high pressure linked to the Azores High – a large semi-permanent centre of high atmospheric pressure – is expected to extend north-eastwards across the UK, while the jet stream shifts further north.

This will allow high pressure to dominate, blocking Atlantic low-pressure systems and leading to a more settled weather pattern, bringing plenty of sunshine, dry weather and another notable burst of summer heat for many.