High winds yesterday forced the closure of the Remarkables ski area, with chairlifts at Coronet Peak also closed for periods during the day.
The wind, combined with "rain-soaked" snow packs, resulted in the avalanche risk rating being upgraded to "considerable", from the previous "moderate" rating.
A "considerable" risk means the snowpack is moderately to weakly bonded in most places, natural avalanches are possible, but human-triggered avalanches are probable and back-country skiing and travel should only be carried out by experienced people, able to evaluate avalanche hazards.
Steep slopes of the aspect and altitude indicated should be avoided.
The council said in the 24 hours to yesterday morning the snowpack had been "rain-soaked" to about 2000m, with a dusting of new snow over Tuesday night.
"Expect pockets of wind-slab to be forming at ridge-lines with any new snow [yesterday].
"Lower elevations will see the snow becoming unsupportive with more rain forecast."
While no avalanches had been reported over the 24 hours to yesterday morning, there was an active storm front approaching the region, and back-country travel was "not recommended".
Remarkables ski area manager Ross Lawrence said as the council changed its warnings, the skifield changed with it.
Mr Lawrence said the decision was made at 7.30am, primarily because of high winds.
"We've had very little new snow to speak of - a dusting came through with the rain [overnight on Tuesday], but wet snow fell.
"All morning [yesterday] the wind was gusting around 100kmh."
Mr Lawrence said the wind had died down by late yesterday afternoon, but with another front expected overnight last night, he was unsure if the skifield would open today.
At Coronet Peak, winds also had an effect, with chairlifts put on "wind hold" for periods during the day.
Ski area manager Hamish McCrostie said at times the wind was gusting upwards of 100kmh, which also forced the cancellation of the adaptive section of the Winter Games NZ Super G racing.
Mr McCrostie said more high winds were expected today, which would add to the back-country avalanche risk.
"If [the risk is] considerable, then there are obviously issues out in the back country. A mix of rain and snow [yesterday] will have avalanche start zones loading with new snow on lee aspects. These south to east aspects must be avoided."
"From our perspective, we'll continue to put the signs out and monitor the borders."
Mr Lawrence said the wind had died down by late yesterday.
