HEALTH warnings have been issued and residents have been warned to expect travel disruption as a heatwave sweeps across the UK.

After a weekend of wall-to-wall sunshine, temperatures in Southampton could hit around 29C by Thursday, shy of the 35.6C UK June record recorded in Southampton in1976.

The mercury shot up on Monday and the highest temperature of the year so far of 29.4C was recorded in London.

The Met Office has said that there is a good chance that the warm weather will continue next week despite showers forecast this Saturday.

Southampton itself is experiencing moderate pollution, meaning that adults and children with health problems should avoid strenuous activity.

And it could get so hot that railway lines between Southampton and London could buckle.

TUC general secretary Frances O'Grady called on bosses to ensure that staff have protective clothing and sunscreen provided.

Urging everyone to take precautions, Met Office forecaster Mark Foster: "High pressure is going to dominate this week so we can expect very high levels of pollen and UV. If you are in the sun you have a greater chance of getting burnt in the short term."

"Long days, very still conditions and clear skies help June temperatures to get very intense. The sun in June is relatively the highest it gets in the sky and heat can build up over successive days."

South Western Railway is urging people using trains to carry water with them to avoid overheating, and drivers are being warned about the dangers of driving while dehydrated.

Research shows that dehydration can lead to slower reaction times, loss of focus, and muscle cramps.

Iain Temperton, Director of Communications at Road Safety GB, said: "Making sure you are fully hydrated is a vital part of that process - the safety of vulnerable road users around you depends upon it."

Very high levels of pollen and UV mean that hay fever sufferers are in for a difficult time, while health experts are urging the public to look out for those who could be badly affected by the heat.

Dr Owen Landeg, of Public Health England, said: “Much of the advice on beating the heat is common sense. For older people, those with underlying health conditions and those with young children, the summer heat can bring real health risks. That’s why we’re urging everyone to keep an eye on those you know who may be at risk this summer. If you’re able, ask if your friends, family or neighbours need any support.

"If you’re going outside for a prolonged period, remember UV is high at this time of year so think how the sun affects you and what you’d do to make sure you don’t get burned," he added.