With the daytime temperatures continuing to romp on, and - more importantly - very high night-time temperatures, the UK Met Office has now declared a Level Three alert for London and the south east. The temperatures are expected to be even higher on Thursday than today.

Level three means that the medical services are automatically on a higher level of standby. 

Measures to take include avoiding unnecessary travel. If you have to go out, try not to go out between 11.00am and 3.00pm. Obviously, this isn't do-able if you're working - my friend T tells me London is currently unbearable - something between an oven and a sauna.

Remember to keep doors and windows closed if the internal temperature is lower than the external temperature. Draw your curtains if they are white or light-coloured (if they're dark, keep them open or you'll only make things worse). 

Watch out for heat exhaustion in these temperatures. Symptoms include:

* headaches

* dizziness

* nausea and vomiting

* muscle weakness or cramps

* pale skin

* high body temperature.

If this happens, move somewhere cool and drink plenty of water or fruit juice. If you can, take a lukewarm shower, or sponge yourself down with cold water.

Be aware that heatstroke can develop if heat exhaustion is left untreated.

The Met Office has raised its heatwave alert for the UK to amber - this means that there is a significant chance that over the next few days, the temperatures will cause significant health risks. Most at risk are the elderly and young babies, but also those with heart and breathing problems, or anyone who is immobile.

If you're not in this position yourself, think of your neighbours who might be and keep a check on them. It does not take very much excess heat for people in these circumstances to get heatstroke - the reason that 15,000 people, mostly elderly, died in France in 2003. Most deaths were not in the searing south, where they are used to dealing with these things, but here in the north, where we're not used to high temperatures. 

Precautions advised by the NHS include:

* Stay tuned to the weather forecast on the TV or radio. If you’re planning to travel, check the forecast at your destination, too. 

* Plan ahead. Stock up with supplies so you don't need to go out during extreme heat. Think about what medicines, food and non-alcoholic drinks you'll need.

* Keep plenty of water to hand and stay in the shade whenever possible.  

* Identify the coolest room in the house, so you can go there to keep cool.

* Avoid going outside between 11am and 3pm as this is the hottest part of the day. Spend time in the shade and avoid strenuous activity.

* Help others. Check up on your neighbours, relatives and friends who may be less able to look after themselves (for example, if they have mobility problems). 

* Drink water or fruit juice regularly. Avoid tea, coffee and alcohol.

* Keep rooms cool by using shade or reflective material external to the glass, or if not possible by closing pale coloured curtains. NB: Metallic blinds and dark curtains can make the room hotter.

* Keep the windows closed while the room is cooler than it is outside. If safe, open windows at night when the air is cooler.

* People with heart problems, breathing difficulties or serious illnesses may find their symptoms become worse in hot weather. Make sure you have enough medicines in stock and take extra care to keep cool.

Managing at Monty

In this house, we are on three floors, including an attic conversion, and the temperature from floor to floor is very different. On the top floor, right now, it is purgatory. Above 28 degrees, we've learned to keep the Velux windows closed, otherwise hot air, heated by the dark slate roof tiles, is drawn in by Venturi effect, making the air even hotter. After nightfall, we go up and open every window wide, allowing cool air to flow through, so sleeping is not a problem - it is only daytime temperatures that are ghastly.

On this floor, where we now have our office, the temperature is middling. I'm sitting here in a strappy dress and it's quite bearable even without a fan. Again, though, the windows are tight shut - it's a lot hotter outside than in. 

On the ground floor, because the walls are stone and the floor is terracotta, it is actually quite cold. We used to draw our curtains shut in summer to keep the heat out, but this is no longer necessary since our green planting has grown up and shades the house quite darkly all summer. Like all the other floors, the doors and windows are only opened at night.

The first summer we spent here, the sun was like an anvil - far hotter than we were used to in Britain - so we quickly planted shade trees and shrubs close to the house. In the South of France, they usually plant plane trees, as these come into leaf late - allowing spring and winter light to enter - then produce huge leaves all summer for a solid canopy that falls quite early in autumn. We have walnuts and sweet chestnuts, which behave in a similar manner (as well as being good croppers). 

Given the more extreme summer temperatures Europe is forecast to experience, next winter might be a good time to think about investing in shade trees or large shrubs if you have a garden big enough. Something deciduous but with large leaves is the best bet: figs, ornamental elders and physocarpus are useful shrubs; virginia creeper, golden hop and grapevines will cover a pergola nicely; while sycamore, maple, plane, sweet chestnut and walnut are all good options for shade trees. 

These are natural, and effectively free, ways to keep cool rather than using fans and air-conditioning, which besides being un-eco-friendly also can't be relied upon if the power fails. 

As Britain cranks up for a heatwave - something Brits certainly didn't get last year - I thought I'd mention in passing some tips for keeping cool:

First, log on to the NHS Direct site and take a look at the Government's advice. A lot of it is 'well doh', but it would seem that some people just don't have the sense they're born with. You'd think things like staying inside when it's hot, wearing sunblock, avoiding alcohol and drinking lots of water would come naturally, but apparently not.

I met some people today in the supermarket just before noon who had been playing tennis in this heat - they're in their 60s. Frankly, this is something I would just not do - leave it to the superfit likes of Federer. I get my exercise out of the way before 7.00am in this sort of weather.

If you can't get out, or have a relative who can't get out, note that the crucial temperature is 25 degrees - you need to keep vulnerable people in rooms at or below this temperature or you're at risk of heat stroke. Cold food, cold drinks, cold water sponged over the body several times a day, cool baths are all de rigeur. 

Back to fashion... Luckily, my days of commuting on overcrowded buses and the like are long-gone, but when I lived in London, here were the things I'd advise to try to stay cool:

* Never go anywhere without a bottle of water on you. You don't know how long you'll be. Suppose the bus breaks down, or the Tube, or you're stuck in traffic in a car. Always, always carry water. There's a huge variety of water carriers and light flasks nowadays - I favour the tin ones made by Thermos that hold about half a litre. If you don't enjoy drinking water, add a bit of orange juice or cordial to it. But whatever you do, keep drinking. How much? Enough to make your urine run clear. The downside, of course, is that you spend half your life in the bog.

* Carry a water mister, such as Evian, in your handbag. This is fabulous for spraying onto your face, hair or neck.

* Carry a cooling gel such as Witch Vera - again, this cools as it evaporates. 

* Carry cologne tissues or a small spray bottle of cologne. Not only does it cool - again by evaporation - but it also kills bacteria stone dead if either you or anyone around you is sweaty. Just be aware that cologne sensitises your skin to sunlight, so it undoes the good of a sunblock. 

* Carry a fan. I'm serious here. The day we got married was a bit of a scorcher but my maid of honour and I did very well with little cheap fans from a Chinese shop - their batteries don't run out, either. 

* Wear a hat to keep the sun off your head. 

* If you're inside, bare as much skin as is reasonable.

* If you're outside, cover up. My fave look is a big straw hat, shades, big white shirt with cuffs that I can roll down to cover my hands, and either a long linen skirt or loose drawstring trousers. Keeping the sun off your skin is far cooler than letting it hit you, and wearing a long skirt means that a: you can go without underwear if you prefer (which I do) and b: you don't stick to bus seats and car seats etc like chicken on a griddle. 

* Stick to colours like white, cream, pale blue and pastels and you'll look as cool as you feel. Pale colours not only reflect the heat better than dark colours, they actually lower your body temperature slightly just by looking at them. Conversely, avoid hot colours such as red, orange and bright yellows.

* Wear loose clothing - loose shifts, sack dresses etc. Tight clothes such as jeans, t-shirts, pencil skirts and belts can be purgatory in hot weather. Don't tuck your blouse in - let a little air flow - and choose a dropped armhole such as on a shirt sleeve to prevent pit stains.

* In general, choose woven fabrics rather than jersey, stretch or knitted items, which hold heat against your skin. The best is probably linen, but a good cotton also works well, especially something tightly woven such as lawn. Cellulose fabrics like cotton and linen are absorbent, and if you pick a weave like organdie, will also stand away from your skin. Organdie used to be the classic fabric for little girls' dresses exactly for this reason. 

* Favour canvas deck shoes or very comfy sandals such as Footgloves rather than formal shoes, especially if your feet swell in hot weather. If you have to wear formal shoes for work, hopefully you're in an air-conditioned building but think about more casual shoes for the commute. Invest in a pair of mules for summer just in case your heels blister. 

* Carry a biggish scarf, either oblong or square, in something like white organza or cotton. You can tie it to a handbag handle for a chic look, but it's invaluable for covering your neckline/shoulders/back of your neck or anywhere you might catch the sun during the day. 

* If you can take a spare blouse to work, keep it in the office fridge and change at lunchtime. I often used to shower at midday, where possible, or at least have a good wash, including feet, crotch and armpits, and reapply deoderant and talc. Same again if you're going out for the evening.  

* Wear your hair off your neck, pinned up in barettes or pony tail bands. A headband also works, and keeping your fringe off your face helps a lot in hot weather. 

* If you work in an air-conditioned building, dress for the heat, not the cold. Wear thin underlayers and keep a warmer top layer such as a jersey cardigan or pashmina in your desk for when needed. It can be a real shock to emerge from a 19 degree office to a street temperature of 30-odd degrees.

* Keep your makeup light and natural - it will only run off like an oil slick anyway. Body Shop papier poudre sheets are great to carry around to absorb any shine during the day. 

If you have any other tips, please send them in.