Experts at the Met Office have issued an amber heatwave alert as children across Kent start their summer holidays.

Temperatures will not dip below 28C this week, with the mercury tipped to reach 30C in Gravesend today.

There is a 90% probability of heatwave conditions from 9am today until 9am on Friday.

Yet the hot and humid air lying over Kent today may turn into thunderstorms in parts of the county by Wednesday.

Forecasters are advising people to stay out of the sun and keep homes as cool as possible.

Shading windows and shutting them during the day may help, opening them when it is cooler at night.

People should drink plenty of fluid and make sure vulnerable people living on their own know what to do.

Kent County Council's deputy director of public health Allison Duggal says while most of us won't have problems, we need to look out for those who might be at risk.

What is a level three heatwave alert?

There is no official definition of a heatwave in the UK, but the term is often used to describe an extended period of unusually hot weather.

The Met Office issues warnings based on "threshold temperatures" and how likely we are to experience them.

If regions reach these temperatures for two or more days in a row there is thought to be a significant health risk.

The threshold temperature across Kent and the South East is 31C by day and 16C overnight.

A level three alert is put in place when threshold temperatures have been reached, and there is a 90% chance that heatwave conditions will continue the next day.

What should you do in a heatwave?

While many of us enjoy the hot weather, it can have serious consequences - especially for vulnerable people.

When there is a level three alert in place, people are advised to stay out of the sun, keep cool, and check on those who might be at risk.

The NHS says the main risks posed by unusually hot temperatures are dehydration, overheating, heat exhaustion and heatstroke.

Tips for keeping cool include having cool baths or showers, wear loose, light clothing and put on a hat and sunglasses when you go outdoors.

Drink cold drinks, keep the curtains and windows shut until temperatures drop at night, and keep informed using the TV, radio and social media.

Who could be vulnerable during a heatwave?

If you're worried someone you know might be at risk, here are the groups of people that the NHS lists as most vulnerable.

• Older people - especially those over 75

• Babies and young children

• People with a serious chronic condition - especially heart or breathing problems

• People with mobility problems - such as Parkinson's, or people who have had a stroke

• People with serious mental health problems

• 6 People on certain medications - such as those that affect sweating or temperature control

• 7 People who misuse alcohol or drugs

• 8 People who are physically active - for example labourers or those doing sports