The Met Office has issued its first ever amber alert for extreme heat and it's covering Cornwall and the south west.

The agency warns that high temperatures both by day and night will continue this week, potentially leading leading to public health impacts.

And it said it could have a knock on impact on safety as more people travel to the coast to escape the temperatures.

It warned to pay particular care to children and the elderly, who could be especially vulnerable to the heat.

The Met Office said: "Adverse health effects are likely to be experienced by those vulnerable to extreme heat.

"The wider population are likely to experience some adverse health effects, including sunburn or heat exhaustion (dehydration, nausea, fatigue) and other heat related illnesses.

"More people are likely to visit coastal areas, lakes and rivers leading to an increased risk of water safety incidents."

It said some changes in working practices and daily routines were likely to be required, adding: "There is an increased chance that some heat-sensitive systems and equipment may fail, leading to power cuts and the loss of other services to some homes and businesses.

"Some delays to road, rail and air travel are possible, with potential for welfare issues for those who experience prolonged delays."

The warning – which is similar to those issued when heavy rain or snow is forecast – covers a large part of Wales, all of south-west England and parts of southern and central England, and will remain in force until the end of Thursday.

It is the first time the warning has been issued since the Met Office said last month that it would launch weather warnings for extreme heat after a record-breaking number of heatwave deaths were recorded in England last summer.

Temperatures are expected to reach 33C in some western areas later this week, with high 20s and low 30s expected elsewhere.

Chief operational meteorologist at the Met Office, Steven Ramsdale, said: “The high temperatures are going to continue through a large part of this week.

"Many areas will continue to reach heatwave thresholds but the amber extreme heat warning focuses on western areas where the most unusually high temperatures are likely to persist.

“There’s a continuing risk of isolated thundery downpours late in the afternoons but most areas will stay dry until later in the week.

"Temperatures should begin to fall for most areas heading into the weekend, with some more unsettled conditions looking to develop.”