THIS week's heatwave has already taken its toll on some people in Gwent, the area's health board has revealed.

Aneurin Bevan University Health Board said it was "already seeing people turn up at The Grange University Hospital who are very poorly due to the effects of the hot weather".

Temperatures are expected to hit 27C in some parts of South East Wales today (Monday) and tomorrow, according to the latest forecasts -- and there are fears the upcoming weekend could bring serious consequences for people's health.

An amber-level weather warning for "extreme heat" has been issued for Sunday, July 17 and covers eastern Wales - including all of Gwent - and most of England.

READ MORE: Temperatures soar across Gwent as Met Office issues heatwave update

The forecast has prompted the health board to issue safety guidance.

"In this hot weather, please take care of yourself and others," the health board said on Monday. "Most of us can enjoy the hot weather safely, but please look out for those who are more vulnerable during the heatwave."

What are the main risks posed by a heatwave?

• dehydration from not drinking enough water

• overheating, which can make symptoms worse for people who already have problems with their heart or breathing

• heat exhaustion and heatstroke

• sunburn

Who is most at risk?

• people who live on their own or in a care home

• people who have a serious or long term illness – including heart or lung conditions, diabetes, kidney disease, Parkinson's disease or some mental health conditions

• people who may find it hard to keep cool – babies and the very young, the bed-bound, and people with drug or alcohol addictions or with Alzheimer's disease

• people who spend a lot of time outside or in hot places – those who live in a top floor flat, the homeless, or those whose jobs are outside