Temperatures soared so high that one house, Issey Miyake, even decided to hand out designer ice packs to the clammy front row.
The label that's known for its functionality shared with fashion insiders a special moment on Thursday.
It was the return of its 74-year-old house founder, who retired from menswear in 1994.
Japanese Miyake, who made a name for himself in technology driven clothes, allowed models to cool down by dressing them in paper.
The other day's shows included big-spender Louis Vuitton — one of the world's most lucrative brands.
It was a slick affair for the menswear designer Kim Jones, who got his feet wet with cool, nautical designs.
The London fashion graduate is quickly making a name for himself for luxurious, yet tasteful designs.
Meanwhile, designers from the Low Countries, Dutch duo Viktor & Rolf and Belgian Dries Van Noten, injected the day with an edgy attitude.
Friday's shows will include Atelier Gustavolins and Givenchy.
Louis Vuitton's Kim Jones presented a deft and confident catwalk homage to the active man.
There was something for yachtsmen, athletes, fishermen — and even safari explorers — in an eminently wearable and wide-ranging collection of sporty elegance.
Might it be that Jones, who is in only his third outing as the house's menswear designer, is trying to impress Louis Vuitton CEO Yves Carcelle, a yachting fanatic?
"I guess so," Jones said backstage.
Whatever the reason, it was a winning formula.
Yellow fisherman's macs twinned with relaxed navy pants and white leather deck shoes to give off one message: we're nautical but nice.
A laser cut blouson in grey was worn by a model sporting a cheeky anchor earring.
Another piece, one of the collection's best, would be sure to help any model stranded at sea: a padded leather life vest.
The show was also kitted out for a safari and then the racetrack.
A series of khaki ensembles merged into skintight scuba tops that could have seen the model break out into a sprint.
Jones' aim was to pull off a "relaxed and soft" collection.
All too aware that too much exercise can be bad for health, he allowed his summer man some R&R in the Cote d'Azur in the form of a series of beautiful check silk suits.
The program notes cited the insouciance of Southern France.
It's Jones who might deserve some time off.
With a few strong collections under his belt, he can — until next season — afford to rest on his laurels.
ISSEY MIYAKE MEN
Issey Miyake's collection marked the return of the Japanese designer to the creative helm in a menswear show of clothes made, incredibly, almost exclusively of paper.
Understatement is an art form in Japan and the behind-the-scenes artistry at work in Miyake's clothes paid tribute to that tradition.
In the past few months, the Issey Miyake design team painstakingly learned the age-old technique of Washi paper bonding, knitting and canvas making. Their teacher — an elderly Japanese lady — is the only surviving expert in the tradition.
Voluminous but stiff cagoules, blousons and jackets in airy white and charcoal black filed by at the Paris show. Their cool, starch stiffness was achieved by bonding paper with rayon before laminating the surface.
Oversized ponchos with knee-length shorts that had sporty yellow markers were achieved by cutting paper into narrow strips and then twisting it to make yarn. They are apparently completely washable.
It was a shame that the designers added another theme into the mix: cycling.
Several models wearing backpacks, which squashed the paper tops, cycled down the runway on bicycles. The sporty distraction was the only element that took away from an otherwise diaphanous ensemble.
Flashes of bright reds and cobalt blues in cool shirts and V-necks reminded spectators it was summer, though it was hardly necessary in the weltering Parisian climate.
DRIES VAN NOTEN
Dries Van Noten is a man of contradictions.
No show demonstrates this better than his surprising menswear collection Thursday for spring-summer 2013.
Camouflage print featured on shorts, pants, shirts and jackets — sometimes even just on strips.
It made the models look like they should run off and hide.
Then fencing gear — such as quilted, white breastplates, and jackets with sword-proof velcro lapels — said "I'm ready for attack."
There was no middle ground: silhouettes were either unstructured and loose or tight and tailored.
Colours were either muted or in flashes of unapologetic electric blue, orange, ochre and canary.
One ensemble had it all: a see-through fencing shirt in blue and white branded with a horizontal strip of camouflage.
To add to the symphony of confusion, this sheer shirt was paired to clash with thick check plaid trousers.
There were some very salable looks: one trendy oversized black, blue and grey knit sweater — a nod back to the 1980s — is sure to be a hit.
Another extremely simple baggy grey sweater and assorted cardigan was pure elegance.
So with such a strong collection — and all its camouflage — what does the designer need to hide from?
"I'm not hiding from anything," said Van Noten backstage, confidently. "That's why I put it on a white catwalk."
VIKTOR & ROLF MONSIEUR
Viktor and Rolf produced a vibrant show with a taste of India — mixing the colours and silhouettes of the subcontinent with their signature suits.
For the very Western design duo, based in Amsterdam, the East seems like an unlikely place to go.
"We were in the mood for something spiritual, sartorial and Indian. ... We liked the contrast," Viktor Horsting said backstage.
The affair was certainly more millionaire than slumdog with wool-silk silhouettes in burnt oranges, deep red, tonal peach and sparkles of Bollywood-style glass appliques.
The Eastern influence saw their normally strict sartorial approach softened in suits. They were less constructed than in previous seasons.
One softly striped suit had a feel of rich Indian linen.
In other looks, jackets were worn with Jodhpur trousers — an Indian garment imported to Europe under Queen Victoria — to create subtle carrot shaped silhouettes.
The dalliance with India, was, however, short lived.
The strongest part of the collection was the interesting variation of the very European herringbone print. It featured in jacquards for tuxedo jackets, and hand drawn for lightweight wool suiting.
When the holiday is over, after all, you always venture home.
Thomas Adamson can be followed at http://Twitter.com/ThomasAdamsonAPSuggest a correction