The trio will then light the Queen's Platinum Jubilee Beacon – if Wellington's wild weather hasn't blown it out.
MetSevice meteorologist April Clark told the Herald while the thunderstorm watch will have expired by the time the ceremony begins, there could still be patches of heavy rain – and Mt Victoria's lookout is often subject to strong winds due to how exposed it is.
"Just because there's no thunder it doesn't mean ideal conditions!"
But rain or shine, Foster says it's an honour to take part in the service.
"It's truly an honour to light the Queen's Platinum Jubilee Beacon, and to do so alongside the two former Governors-General, on behalf of all Wellingtonians and, indeed, all New Zealanders to mark Her Majesty's remarkable 70 years of service."
Te Ātiawa and Ngāti Toa Mana Whenua – the local tribal authority representatives of Wellington City – say Māori recognise the traditional use of lighting sentinel fires referred to as Ahikā – the eternal home fires.
"The sharing of the fire represents two peoples unified. The local tribal authority beacon and the Queen's Platinum Jubilee Beacon simultaneously represent our Treaty of Waitangi partners."
While the event will be livestreamed, the physical event will be closed to the general public - as part of this, the lookout and carparks at the top of Mt Victoria will be closed to the public for the event from 11am on Wednesday 1 June till 11pm on Thursday.
In addition to the beacon ceremony, the MIchael Fowler Centre and Carter Fountain will be lit in purple in honour of the Queen between June 3 and 6.