อากาศเซี่ยงไฮ้ เดือนตุลาคม

True story. There was to be a big APAC meeting in Shanghai in October 2001. They literally stopped all factory work for two weeks prior so that the skies would be blue when all the dignitaries arrived. I gotta say it was glorious!

Regulars are consistent this is a damp cold rather than a dry one, wind and moisture together making the air feel considerably colder than the actual number suggests, biting hardest at the extremities - scarves and gloves specifically recommended over one heavy coat. Our row backs the chill, 12C reading as 9C over 3.4C nights feeling -1C, with 35.2mm of rain across 6.3 days and a trace of snow, 0.5cm, alongside a real 17.7 kph wind. Regulars are clear this month rarely brings snow itself despite the cold, and that smog is a real, separate concern worth checking forecasts for on top of the temperature. Layering beats one bulky coat, since winter weather here swings enough day to day to make flexibility the more useful strategy. The record: humidity 72 percent and AQI 156.

There is a local saying regulars quote here - the cold in spring is really cold - and it is about damp rather than degrees. March brings little snow and plenty of grey: our row gives 16.3C by day reading as 14C, 7.1C nights that feel like 4C, and only 7.1 hours of sun a day at 76 percent humidity. Their packing answer is layers and a light windproof rather than winter gear, with something waterproof for the 81.2mm that falls across 10.2 days. The month's other cost is in the air column at AQI 117. A 19.5 kph wind is the reason the felt figures sit two to three degrees under the readings. The record: a dew point of 6.1C.

Regulars give late November here as about 16C in the day and under 10C in the evening, cold and windy but reasonably dry, with the genuinely hard winds holding off until late December. Our row averages 18.4C over 10.3C, reading as 17C and 8C in a 17.8 kph wind, with 59.8mm across 7.3 days. They rate October the better month on two counts - warmer and historically cleaner air - and our AQI of 110 does not argue. On autumn colour they are honest: the city does not do it well, mid-November is the best of it, and Suzhou or the botanical gardens are where to look. The record: humidity 75 percent and 6.4 hours of sun inside 10.6 of daylight.

May in Shanghai is warm and, by late in the month, humid - 18 to 28C on the forum's reckoning - and it is also the tail of the spring rains, which run from about mid-April to the end of May and can mean two or three straight weeks of grey drizzle. Our row carries 127.4mm over 11.1 days. The date that matters more than the weather is Labour Day: the holiday is 1 May but the break runs roughly the 1st to the 5th, most people take a long weekend from 30 April, and the crowds build from the Friday - everywhere twice as busy. Mid-April is the cooler alternative. The record: 25.7C days that feel like 28C, 16.8C nights and AQI 98.