During the breakfast program on Monday, Kochie revealed Nat had been struck down with Covid and has been in isolation.
"Everyone's asking, 'Where's Nat?'" he said.
"You may have noticed she's been missing over the past week or so, she's at home in isolation after testing positive for Covid."
Monique Wright, who is filling in for Nat, said the host had been keeping busy trying out new recipes and organising her wardrobe.
"Doing some early spring cleaning and organising due to being stuck in her bedroom," she said.
Kochie added she had also been cleaning out her bathroom cabinet, evidence of how "bored" she is.
"Nat said she might start on her sock drawer today, she says she's feeling pretty good, she's fully vaccinated, had all the four doses and her cough is virtually gone," he said.
"We wish her a speedy recovery."
Monique then said she was surprised by how much Nat was achieving in isolation, adding they had been swapping TV shows as Monique had recently been isolating with Covid.
"She's getting through a lot of TV, I don't know how much cooking and sock drawer organising is happening," she joked.
Kochie added Nat was expected to be back behind the desk on Wednesday.
Her absence comes after Kochie was absent from Sunrise for three weeks to attend his daughter's wedding in the UK.
He returned on July 18, when he admitted he broke down during his daughter's wedding reception.
“At the reception, during the speech. Which I do for all of my kids' weddings, but I thought [for] the fourth one I’d better make up some emotion, just so Georgie doesn’t feel out of it,” he joked.
“I lasted for the first half a sentence [before crying]. It is so emotional when your kids get married,” he told Nat.
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