The couple's Caribbean tour has been dominated by the debate over the United Kingdom's role in the slave trade but it was the sight of the soaked monarch which made headlines on Sunday.
As the rain hammered down on Charles, 77, he was seen gesturing and turning round to try to attract the attention of someone who might help, while Camilla was shielded from the downpour at the Sir Vivian Richards cricket stadium.
The King appeared to mime holding an umbrella and repeatedly said to members of his entourage: "Where's the umbrella?"
Queen Camilla was quickly handed her see-through dome umbrella and rushed to nearby royal seating and later saw the funny side of the moment.
Locals taking part in the Antigua and Barbuda independence day parade did not flinch as they were lashed by the storm.
Charles was eventually given an umbrella and was seen joking about his experience with Prime Minister Gaston Browne. "I think I'm about to grow watercress on my suit," he said in a video posted on the royal family's Instagram account.
It is not the first time the frustration of the famously short-fused Charles has been captured in public.
Not long after he became monarch in 2022 in an incident which went viral on social media, he reacted grumpily when a pen leaked ink onto his hand at an event in Northern Ireland.
"Oh God, I hate this," he cursed.
"I can't bear this bloody thing... every stinking time," he continued.
He has since made fun of himself, quipping at a subsequent event, "I'm hoping that my pen is going to work. It doesn't usually".
He is due to make a speech to Commonwealth leaders on Tuesday.
Since becoming King, he has expressed sorrow for the suffering caused by slavery without crossing a line that the UK has long resisted: an apology.
with PA
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