THE county sizzled in the sweltering heat yesterday, but experts have warned that the good weather may not last long.

Temperatures in Oxfordshire soared to a red hot 31C – 3C higher than Rio de Janeiro in Brazil – yesterday, but in typical British summer-style,the Met Office is predicting a dip to 24C today with a risk of rain and thunderstorms.

Tomorrow temperatures are going to rise back up to 27C, with potential showers in the evening.

Deputy chief meteorologist and Met Office spokesman Steve Willington, said: “The warm air means there is a risk of us seeing thunderstorms today, but the exact timing and location, if they happen, is uncertain.

“Most areas will see warmer temperatures again tomorrow although it may well be cloudy at times with a risk of rain spreading from the south by the evening.”

Richard Taylor, general manager of Hinksey Outdoor Pool in South Oxford, was undeterred by the news, He said: “Our pool has been completely full, even on school days.

“As soon as the sun came out we had 200 people in the swimming pool and 100 others in the grounds sunbathing or watching.

“It’s a shame that the weather isn’t going to be so great for the rest of the week but we’re hopeful that we’ll get more people in on the weekend.”

Six-year-old Josiah Haines, who took a dip yesterday, said: “I haven’t been in the pool for ages, but it’s really warm. I think I’m going to stay in for a very long time.”

St John Ambulance and Public Health England warned that the high temperatures could still be dangerous for residents, with the elderly and young children at particular risk.

In the 2003 heatwave, there were more than 2,000 more deaths in England than usual.

Clive James, training officer at St John Ambulance said: “Extreme heat can be dangerous, but by being prepared you can spot the early warning sign.

“Heat exhaustion and heat stroke are the most serious problems that can develop when the mercury soars, so it’s essential that people can spot the signs, such as headaches and dizziness, and get the sufferer somewhere cool and rehydrated as soon as possible.”

Public Health England’s Graham Bickler said: “Most of the information is common sense, it’s not rocket science, but it can have a dramatic effect.

“Try to keep bedroom and living spaces cool, by closing the curtains on windows that receive the sun and open your windows at cooler times of the day and overnight.”

The weather caused rail chaos yesterday evening, with 20-minute delays to and from Paddington and between Oxford and Didcot.

Problems were made worse after a train broke down between Oxford and Worcester, leading to delays and cancellations on the Cotswold Line.