Organisers were hoping forecast rain would ease to occasional showers but, if not, the races would still be happening.
"It'll go ahead no matter what.
"It would be unfortunate if it's wet, we had a wettish day last year."
Late registrations can be made between 10am-2pm Saturday at the Havelock North Function Centre or Sunday morning before the races at Farndon Park.
Longman said he was particularly looking forward to seeing a team from the Waimarama Surf Life Saving Club carry their IRB raft on the 3km course.
"If it's a wet day there might be water inside it rather than outside as usual.
"They are putting in a group of 10 to transport it."
Buses go from Farndon Park in Clive to the start of the events.
Dogs are welcome on all of the courses and on the buses but must be on a lead.
Race numbers can be collected between 10am and 2pm from the Havelock North Function Centre on Saturday.
Participants can take part in a 3km, 8km or 17km walk or run.
The 3km walk/run event will start from Waitangi Reserve and finish at Farndon Park.
The 8km walk/run will start from Grange Rd in Haumoana and end at Farndon Park.
The 17km event will start from Riverlands carpark in Havelock North, before meeting up with the 8km course at Black Bridge.
The bus for the 17km event will leave Farndon Park at 7.45am (walkers) or 8.45am (runners), 8km at 8.45am and 3km at 9.45am.