STAY out of the sun, drink plenty of fluids, wear light, loose clothing - and DONT drink alcohol.

That's the advice from a top York GP as temperatures in York are predicted to peak at up to 40 degrees C tomorrow.

Dr David Fair of the Jorvik Medical Practice said it might be tempting to sink a pint of cold beer as the temperature rises.

But he said that was the wrong thing to do. Alcohol acts as a diuretic, which means it can lead to the body becoming dehydrated - the last thing you want in soaring temperatures.

"If you drink a pint of beer, you will lose more than a pint of fluid," Dr Fair said. 

Instead, he said, people should stay out of the sun and drink plenty of non-alcoholic cold drinks.

It was important to take the warnings about the high temperatures seriously, he said. Heatstroke could come on without you realising. "And it is potentially fatal."

Dr Fair said children, eledrly people and those with pre-existing heart or lung problems were most at risk of heatstroke.

Children tended to get excited playing out in the sun, and not realise how hot they were getting, he said.

Elderly people, meanwhile, lose some of their sensitivity to heat changes so sometimes might not realise they are overheating.

They also lose some of their sense of thirst - so are less likely to realise they are getting deyhdrated.

But heatstroke can affect anyone if they don't behave sensibly, Dr Fair said.

The body temperature rises -sometimes without you realising. With a higher body temperature, you metabolism speeds up - pushing your temperature even higher.

You might start feeling faint and nauseous - and may even start shivering as your temperature regulation mechanism stops working properly.

You could then begin to feel disorientated - any may eventually collapse into unconsciousness.

Dr Fair said most people were aware of the warnings about extreme heat - but, because heatstroke could catch you unawares, it was important to be sensible.

He said people should keep windows closed during the day to stop warm air getting into the house - and open at night, to allow cooler air to circulate.

If you do get too hot, one good way of cooling down, he said, is to splash cold water over your head and hair. "We can lose a lot of heat through the head."

Drinking cold drinks would also help to bring body temeprature down.

If someone falls ill from the hear, you should try to cool them down. if they lapse into semi-consviousness or unconsciousness, Dr Fair said, dial 999 - otherwise call 111, but keep monitoring their condition.