Temperatures are back to 'normal' in France the past couple of days - a bit lower than normal, actually - but we had been basking in a heatwave for a while this past week or so.

Thirty-degree heat for days on end gave me the opportunity to rediscover the delights of wearing yukata.

Yukata are a form of Japanese kimono that are worn as bathrobes, sometimes for sleeping, and for casual wear in spa resorts and at the coast. Made usually from cotton, though sometimes hemp, and often in the colourway blue and white, they are the most wonderful, comfortable, airy garments you could imagine. Japan has a hot, humid climate in summer and the Japanese know a thing or two about how to keep cool.

I have a sizeable collection of vintage kimono, but until now, only two yukata - one in polycotton, a gift from a friend, and the one shown above, in a cotton 'ro' - a fabric woven with thousands of tiny holes that look like hemstitching and allow air to pass right through (see bottom picture).

Having lived in these for a couple of days, along with a silk ro kimono that was almost equally cool, I splashed out on three new ones - two worn vintage and one overstock from a shop clearance. I've always wanted a yellow yukata (the one above was 10 dollars); the floral one below (four dollars) is just gorgeous and has these lovely curved sleeves, and the stencilled one (99 cents) is in cotton Ro for maximum coolth. 

One of the reasons yukata are so comfortable in the heat is that - as with all genuine women's kimono - they are open under the arms. From where the sleeve meets the side body, the body is open for about eight inches, and the back of the sleeve is also open to the wrist. This is to prevent the kimono from binding when you wear a deep obi sash, but it also allows the free passage of air where you would otherwise be the most sweaty.

Kimono are traditionally worn wrapped left over right (in Japan, only corpses wear them wrapped right over left), but since I'm a westerner I feel no need to uphold tradition in this way, and I wrap mine right over left because it feels more natural to me. I hitch up the overlength, sash it with a narrow cord around the waist, drape the rest freely around the hips and sash it closed around the waist with a long silk scarf. I close the neckline with a brooch.  

The kimono at right, with the long sleeves is a different kind of summer kimono - silk gauze, known as 'sha'. This stiff, transparent, featherweight silk stands away from the body rather like silk organza, so it feels like you're wearing nothing at all. Sha silk kimono are far more formal than cotton yukata, and in Japan would always be worn over an underkimono, but since I work from home, I wear mine as yukata. Nothing is more comfortable when you're working at a desk all day. 

You might think that the sleeves of kimono would get in the way, but personally I don't find this. The shorter, curved sleeves stay out of the way, while the longer sleeves can be tucked into the side body when you're working, or tied back with a cord.

The big surprise is to see how addicted the DH has now become to kimono. Back in the winter I suggested that he wear a wool 'juban' - a kind of underkimono - as a top layer, and he found it so comfortable that he now practically lives in it, swishing around the house from morning to night. So I've just ordered him a yukata as well - this 1950s number in splashy cotton.  Note the different shape of the sleeves - indicating a man's style. The side body and sleeve are also closed, for those of you who prefer to be more covered up. 

When it comes to talking about kimono, I'd better confess an interest. I am a kimono addict - I have over 80 of the things, all vintage, and all bought on Ebay.

This isn't something you could do even 10 years ago, but with the rise of the Interwebs, you can now get kimono direct from Japan for very modest sums, plus about $12 postage and upwards (it depends on weight). They date from Victorian times (the Meiji era) onwards, but the majority are from the 1960s or more modern, and many have either not been worn, or show hardly any wear.

I am not talking here about the long kimono we're all familiar with, that you can wear for dressing gowns and for lounging around in. I do have a bunch of those, and will write about them another time, but what many women don't know is that there are kimono jackets too, which are eminently wearable over normal Western clothing. These go by various names such as hanten, michiyuki and hippari, but the ones that are really interesting from a fashion viewpoint are called haori.

Haori come in various lengths, from hipbone to about knee-length. Unlike a full-length kimono, which wraps over, a haori is designed to be open at the front, and it has long, turned-back lapels, and ties that fit across the bustline. These long lapels give you a slimming vertical line that is very flattering.

Haori are also very beautiful objects in themselves. As with all Japanese traditional garments, because the shapes hardly vary, all the design energy goes into making the fabric gorgeous. Therefore haori come in a very wide range of colours and patterns, from plain black to screamingly bright, and use all kinds of techniques in their manufacture, including hand-painting, shibori tie-dyeing, embroidery, applied goldwork and metallic brocade weaving. They are almost all made of silk.

Although you needn't go as nuts with haori as I have, even one is a great addition to a wardrobe and gives you a chance to own genuine art-to-wear. More times than I can mention, people have crossed restaurants to ask me where I got mine from, and my sister has had the same results with one that I gave her. Meanwhile, my MIL wears hers indoors as a warm lounging jacket. Some haori linings are so beautiful that western women prefer to wear their haori inside out, as I am doing in this picture.

How to wear them

When you wear a haori, you should pull the collar down at the back, away from your neck, and then the front will fall properly. This feels a bit odd to a westerner, but Japanese garments aren't designed to fit close to your neck at the back, as you can see in this picture. Haori are voluminous, but if you have a fuller bust, you may find the central gap is still too wide. In this case, you're better off flipping the lapels forward (they're often held with cross-stitches that you have to snip), ironing them flat and holding them shut with a long pin or with ties. Quite often, what I do is use proper haori cords (these are like short, thick, woven ribbons) looped around a couple of buttons sewn onto the front lapels.

Haori are easier to wear than you might think, so don't be put off by the long, dangling sleeves. Obviously, you won't want to do the washing-up in one but eating at a table, for instance, isn't difficult. If you have to lean over the table, just hold the sleeve out of the way with your other hand (this is what the Japanese do), but while you're actually eating, the sleeve is kept out of the way by the table edge. You can easily wear a haori to go out to a restaurant, or for evening events such as the theatre or cinema, on top of a black dress, skirt or trousers, or even over jeans. For stand-up events, choose a haori with a beautiful design on the back - many of these are plain black at the front and function like a tuxedo jacket. I wear my single-layer transparent haoris over bright clothes that I want to tone down, while longer haori make lovely evening coats: my favourites are in the technique known as 'urushi', which is metallic brocade weaving.

How to buy them

I buy my haori on Ebay, and the following vendors are foolproof: Yamatoku, Ryujapan99, Ichiroya. However, there are many other reputable vendors - look for those with very full descriptions, and LOTS of crisp photographs, including close-ups or a map of any stains or wear. Start with something fairly cheap in case you're hit for Customs Duty and until you get a feel for things (but be warned - once you get the bug, it can be difficult to stop). This pictures shows a 1930s haori with hibiscus pattern and a bright lining - you can't tell from the picture, but it is very long, almost knee-length on me.

Here's a brief glossary of terms you might come across when buying vintage haoris.

Rinzu - silk jacquard weave which may be used shiny or matt-side out.

Omeshi - thick, heavy, glossy silk of almost furnishing weight, often coupled with urushi (see below)

Meisen - thick, glossy silk like a thick taffeta

Chirimen - silk crepe with a matt finish and flattering drape

Urushi - metallic brocade weaving usually in gold or silver

Yuzen - hand-painted dye technique

Bokashi - watercolour effect (usually a print)

Shibori - tie-dyeing, often in tiny dots that give the fabric a texture similar to seersucker