He had set out to visit his partner’s family and also to meet members of the Kerala State Assembly, but instead was brought face to face with the after-effects of a disaster reckoned to have caused the loss of around 400 lives while making a million homeless.
The flood is the worst to hit the area for a century.
Monsoon rains forced the closure of his original destination airport, Cochin, and he soon saw first hand the carnage wreaked on communities which have lost everything.
Buildings were swamped and people forced to flee to temporary rescue camps as a massive relief operation began to get underway.
Taken on a tour on some of the villages affected he was shocked by the extent of the damage, and saddened by the misery it has caused - but also heartened by the community’s ability to pull together.
Commenting on social media, he said: “I have been very impressed by the strength of community, and how everyone is working together to bring relief to those affected.
“Truly touching to visit and speak with residents from Kuttanard at a relief camp - their village is in the worst affected area and is still submerged in water”.
Despite the scale of the disaster he says the rescue operation has successfully saved many hundreds of lives, and the focus now is moving to the mammoth task of clearing away the debris and trying to restore life to some sort of normality for thousands of traumatised victims.
That will involve a daunting rebuilding challenge, and relief work - which has included help from across the world, including the UK’s Kerala community - is still in its early stages.
Meanwhile livestock has suffered worst, and the carcasses of dead animals pose a grim threat in a landscape in which roads have been swept away and bridges destroyed.
Mr Day told a newspaper he aimed to contact the Department for International Development on his return to the UK, in hopes of channelling expert assistance to the areas which need it most.
Reports suggest Kerala’s roads, public buildings and infrastructure have suffered around $2.7bn worth of damage, and - besides the loss of life - as many as 200,000 homes have been wrecked.
Nevertheless the Indian government has declined offers of aid from the United Arab Emirates, and appears determined to tackle the disaster using mainly domestic resources.
According to the Financial Times this has sparked fierce criticism from Kerala’s state government, which it says was already under financial pressure before the flood disaster struck.