Abasic climatic equation might go something like this: where the sun shines, it is warm; subtract the sun and the temperature drops. In this sense, Bangkok is an anomaly. As the sun disappears, the clouds refuse to follow, sealing the miasma of heat over the city for another night. Quite simply, with your eyes closed it's not easy to differentiate day from night.
Still, I'm as cool as a cucumber as I sit at the chef's table in the Mandarin Oriental hotel's Thai restaurant, Sala Rim Naam. Celebrity chef Vikit Mukura breezes into the refrigerated chamber of his vast kitchen complex to dish up a menu of innovative twists on familiar staples – a tom yum cocktail with lemongrass, chilli, galangal, kaffir lime leaves and soda; khow fu pla fu, an old-fashioned street snack made with puffed jasmine rice, shrimp, chilli, sugar and salt; red curry with a huge scallop; and a cool, milky ice cream made with rice from chef Vikit's paddy field in Pattaya.
After three hours in the air-conditioned kitchen I've forgotten all about the hot, steamy city outside. But by 10.30pm, the temperature has barely dipped below 30C and as the doors part I'm reunited with its stifling embrace. There's nothing for it, so I throw caution to what little wind there is and duck into a tuk-tuk bound for Patpong. The air rushes past as G-force thrusts me back into my seat, my fists clenched on the rails and feet planted at either corner of the disco-lit passenger compartment as the little three-wheeler goes full throttle up Silom, the main artery of the city's commercial centre.
Patpong fulfils all the clichés about Bangkok. These two small streets that channel off Silom comprise the world's most infamous red-light district. Owned by a family of Chinese immigrants since the 1940s, Soi Patpong 1 and 2 were once innocuous strips of shophouses, but the wave of American soldiers arriving in Bangkok for R&R during the Vietnam War soon brought a more hedonistic attitude to the area. The seediness peaked in the 1980s and while much of the (officially illegal) sex tourism trade is now focused in other parts of the city, the lurid fluorescent signs of the go-go bars, the touts thrusting laminated menus of ping-pong balls, bottle tops and bananas at you, and open doorways revealing scantily clad girls parading along bar-tops leave little to the imagination.
Nowadays, Patpong is more comical circus attraction than illicit enclave, where tourists come to gawp, take a picture – and shop, because it's the beckoning going on in the middle of the street that's attracting the most attention. The Patpong night market is one of Bangkok's busiest, flogging fake Prada bags, Diesel jeans, Ray-Bans, Hello Kitty T-shirts, Chang beer vests, Thai boxing shorts, fake watches and pirate DVDs. "Nice price," the vendors chant, as I weave through the packed crowds of browsers. The theory seems to be, sell it and they will buy – and we do, seemingly regardless of the provenance of the goods. The temptation of a bargain is irresistible and I walk away with a new nice bag and strings of paper lanterns for the equivalent of £25. To one side of the plastic awnings and strip-lit stalls, air-conditioned shops selling real-leather versions of the bogus bags offer a more refined environment for bartering your Celine Phantom tote down from 17,000 baht (£360).
According to Mastercard's Global Destination Index, Bangkok has overtaken London to become the world's most-visited city, with almost 16 million visitors projected for this year, nearly double the number of its population. Its overnight visitor-spend is an impressive £9.5bn in sterling terms, with Chinese tourists accounting for one of the highest spends, an average of £111 per day. Their interest was piqued last year by the hit movie, Lost in Thailand, much as The Beach did in the West and The Hangover Part II didn't. But it's shopping that has fuelled their enthusiasm, particularly Bangkok's shiny mega-malls such as Siam Paragon, a temple of duty-free discounts and every conceivable permutation of global luxury.
Poised somewhere between this refined take on the Bangkok retail experience and the gaudiness of Patpong is Asiatique. Perched on the banks of the Chao Phraya, it requires only as much as a serene breeze along the water to reach it. From Taksin pier, I step aboard the free shuttle and head along the river past elegant bulb-lit teak barges and raucous party boats, arriving five minutes later outside the vast open-air mall. Once again, neon lights up the night sky, but this time it's a 60-metre-tall illuminated Ferris wheel that heralds my arrival.
It's a markedly Western experience – a village laid-out in a Disneyesque interpretation of retail perfection. The market sits on a former plot of warehouses belonging to the Danish-owned East Asiatic Company, some of which have been retained and renovated so that it appears to be a much more ersatz colonial experience than anything with historic character. It opened last year after the closure of the Suan Lum Night Bazaar near Patpong and offers a condensed selection of just 1,500 shops and 40 restaurants that open from 5pm to midnight.
The low-rise, colonial mercantile-style buildings are immaculately painted in cream, with faux tram-cars forever halted on the pedestrianised avenues and empty water tanks perched on the roofs. Softly-lit stalls peddle anything from tin tuk-tuk trinkets to jasmine-scented bath oils and chic little dresses, with not a tout in sight or earshot. What's notable here though, is the clientele – while I join a small number of tourists browsing, it's young locals who make up the bulk of the crowd, eating in the restaurants and chatting away on benches.
Some say this is the future of Bangkok's legendary retail culture. While old sprawling bazaars are being closed down as their valuable plots are sold on to developers, and the traditional floating markets of the khlongs (canals) have all but disappeared as the waterways make way for roads, there's growing demand for an air-brushed, hassle-free experience.
But if you want a flavour of Bangkok without tacky bars or conventional malls, it's there – just aim for Sukhumvit Road, the congested commercial route that runs through the heart of the city out to the coast. I get off the immaculately clean and cool Skytrain monorail at Thonglor station and follow my nose to Soi Sukhumvit 38. On this narrow side street – opposite a Tesco – queues are forming under a tantalising cloud of piquant aromas, aimed at two rows of strip-lit food carts.
There's sticky rice with mango, pad thai, green curry, roast duck and barbecued squid, with plates selling for little more than 40 baht (85p) that are devoured at plastic tables. It's hot and noisy, but the steady stream of shop workers, families, tourists and clubbers is testament to its calibre. You might be able to buy a Lamborghini at Siam Paragon, ride Thailand's highest Ferris wheel at Asiatique and drink a cocktail version of the legendary tom yum soup at the Mandarin Oriental, but there's still an appetite for cheap, authentic food, eaten right at the point of sale in Bangkok, night or day.
The writer travelled with Kuoni (01306 747008; kuoni.co.uk), which offers three nights at Mandarin Oriental Bangkok, with Eva Air flights from Heathrow and private transfers, from £1,140pp (quote, KU0703).
Mandarin Oriental, 48 Oriental Avenue, Bangkok, Thailand (00 66 2 659 9000; mandarinoriental.com/bangkok).
Asiatique, 2194 Charoenkrung Road, Wat Prayakrai District, Bangkor Laem (00 66 2 108 4488; thaiasiatique.com).
Tourist Authority of Thailand: tourismthailand.org