Month of Downpours Ahead as Plum Rains Hit Shanghai

By Ned Kelly

You see that rain outside your window? We're afraid you'd better get used to it, as the plum rain season – or meiyu – is upon us.

Expect rain, rain and more rain over the next few weeks; The Weather Channel is forecasting thunderstorms on 13 of the following 14 days alone. On the other day it is merely 'rain.'

The joys...

Image via The Weather Channel

The plum rain season officially started today – Wednesday, June 19 – two days later than last year, and bang on schedule. It lasts 23 days on average.

Time for a brief plum rain history lesson. First up, some 2023 facts and figures:
  • It started on June 17 and lasted 24 days – three days longer than average
  • It was the hottest plum rain season for 17 years – since 2007
  • The average temperature in the city was 27.8 degrees Celsius – 1.8 degrees higher than normal
  • The average precipitation was 348.7 millimeters – 50% more than usual

It gets worse; in 2021 it went on for a month. And in 2020 it got all Biblical, with the deluge lasting 40 days and 40 nights.

READ MORE: This is the Longest Plum Rain Season in 20 Years... and Rising

Finally, let's all get on our hands and knees and pray for no repeat of 1954, the longest plum rain season in history at a bone-soaking 58 days.

What are the Plum Rains?

The East Asian rainy season, or meiyu (literally 'plum rains' – the fruit ripens during this period) usually starts in June and can last all the way into August.

It is the result of a weather front (a boundary separating two masses of air of different densities) that is created when the moist air over the Pacific meets the cooler continental air mass.

When the moist air is cooled, the water within it condenses into drops heavy enough to be pulled down by gravity and, well... raindrops keep falling on our heads.

This front moves back and forth as the cool and warm air masses battle it out, ending only when a warm air mass from the south, associated with the subtropical ridge, is strong enough to push the front north and away.

Be careful wishing for that subtropical ridge, though: not only does the mercury soar to uncomfortable levels; most tropical cyclones form on the side of it, which means monsoon season.

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[Cover image via Pexels]

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