Charteris said the change in dates this year to early February, instead of March, had paid off. He said the fire risk was lower this time of year.
"We studied 10 years of weather records ... and found we always get a bit of rain before Waitangi weekend."
Charteris said they had a fantastic field of elite runners this year.
The field boasts runners like Michael Wardian (USA), who holds the 50km indoor world record, and Kiwi star Vajin Armstrong who regularly features on the podium at the Tarawera Ultra.
The 2013 and 2014 men's champion Sage Canaday (USA) is not taking part this year, because of injury, but the women's defending champion Jo Johansen (Wellington) is returning. Johansen will have plenty of competition in the women's 100km race with the likes of fellow Kiwi Ruby Muir and Nuria Picas-Albets (Spain) entered. Rotorua's very own Shannon Leigh-Litt is also among the female elites in the 100km race.
The Tarawera Ultramarathon is part of the Ultra Trail World Tour which includes 11 races across the world.
The ultramarathon event was given $300,000 by the Government last year to help build its international profile.
Charteris said entry numbers from overseas runners had doubled this year with about 350 internationals taking part.
"There has been big increases from everywhere - North America, Australia, Asia, Europe."
Charteris, who has been in charge of the Tarawera Ultramarathon since he founded the event in 2009, will take part in his own ultramarathon for the first time tomorrow.
Local runner Tim Day will take over the race director duties as Charteris looks to complete the 100km event.
Charteris said his training had not been ideal ahead of tomorrow's event, juggling work and training, but he had still managed to get quite a few kilometres under his feet.
The race gets under way at 6am tomorrow (for all three distances) outside the Redwoods Visitor Centre. The record time for the 100km event is 8hr 33min 50sec set by Sam Wreford in 2011.
