There Ardern will be expected to drink kava, a traditional ground root drink that looks like muddy water, from a coconut shell, before making a brief address.
From that ceremony she'll go to nearby Government House to plant a tree as part of Fiji's climate change plan to plant 30 million trees over the next 15 years.
She will then sit down to a formal meeting with Bainimarama where climate change issues are expected to dominate. Bainimarama is seen in the Pacific as leading the way. That is likely to be in stark contrast to her meeting with Australian Prime Minister Scott Morrison in Sydney on Friday. Morrison is seen as lagging behind other leaders when it comes to climate-change initiatives.
Ardern will conclude the formal part of her day with a meeting with opposition MPs. A scheduled meeting with the first military strongman Sitiveni Rabuka, who is now opposition leader, was cancelled when it was discovered he wasn't in the country.
Her day will conclude with a state dinner hosted by Bainimarama.