Both teams have been among the top fundraisers for the event, with Cromwell generating more than $4000 and Alexandra more than $1500.
In total, more than $35,399 has been raised so far for New Zealand's Leukaemia and Blood Foundation by the 53 teams and individuals participating in this year's event.
Alexandra and Cromwell's teams of eight and nine volunteer firefighters respectively have been in training for the past four months.
This week, all their hard work will be put to the test as they represent Central Otago when competing against other firefighters from New Zealand and overseas.
Ranging in age from 19 to 50, the Alexandra team members, of which two are women, have been given free use of the ProActive Fitness Centre in town, as well as training advice from coach Rob Davidson, who owns the gymnasium.
Mountain biking, cardio-training, weights and ascending the Alexandra "clock hill" had prepared team members for the gruelling 47-floor race, team leader Mark Hutton said.
In similar style, Cromwell's firefighters have used most of the 159-step staircase at the Clyde dam.
Individual and team relay titles are the focus of Saturday's event, which involves firefighters going up the 328m Sky Tower in full uniform.
With 1029 steps, it is the tallest building in the southern hemisphere.
Organisers hope this year's fundraising can surpass that of 2008, when $94,000 was generated for the Leukaemia and Blood Foundation.