I'd asked Mrs P if she'd ever heard about this earlier in the week, she just said 'yes' but 'old'.
Found these pics from 2019 at Khlong Narai, eastern Chanthaburi
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Traumatising for the cat.
The cat is to be drenched with water so that it 'sings' constantly to call for rain.
As the parade goes around the village money is collected which is donated to the local monks along with food the following day (no surprises there).
In other news
Six cloud-seeding / rainmaking planes based near us, understand that as well as for local orchards they're flying north to Sa Kaeo, south to Trat. When it does rain, maybe June, they'll naturally take the credit.
And a local trucking company has several trucks each with 6 x 1000 litres tanks loaded, going to houses outside town who not on town-supply water to stock up their tanks. All for free, a case of 'merit' I suppose