Spring weather swings are causing havoc in Fiordland National Park, affecting the Great Walks as well as other tracks, and literally throwing logs at the feet of the Department of Conservation (DOC) rangers.

After an unseasonally warm early spring came heavy snowfalls at the start of November, followed by more hot and dry weather. 

The Kepler Track was particularly hard hit. In the Iris Burn Valley alone, snow and wind caused 50 windfalls on the track, according to DOC Principal Ranger, Recreation/Historic Fiordland District, Grant Tremain. This happened just six days after DOC staff completed the clean-up of the Kepler Track in preparation for the new season and for the Kepler Challenge, forcing them to start all over again to get the track ready for Te Anau's biggest annual event.

"We worked it into the schedule and made it a priority. We had to pull staff off other projects, but the track is now ready for the Kepler Challenge," Mr Tremain said.

Trampers coming off the Routeburn, Greenstone and Caples tracks also reported seeing a lot of tree damage caused by the unseasonal snow. Clearing the trees that block the tracks is hard work for DOC hut rangers who have to work with hand saws and axes, leaving the bigger logs to chainsaw experts.

At the other end of the weather spectrum, recent hot dry conditions create different challenges, mostly around the availability of water. Huts and campsites are supplied by streams or rainwater. With little or no rain there is a risk of streams running dry and tanks being drained empty. 

The Kepler Challenge creates additional demand on the water supply at the Luxmore, Iris Burn and Moturau huts, as the hut drink stations use the hut water, although containers of water are flown up to the two high drinks stations at Forest Burn and Hanging Valley. Race organisers have to take this into account to make sure trampers and race participants are not left high and dry. However, the chairman of the organising committee, Steve Norris said this has never been a problem in the past.