Interest in the Tongariro Alpine Crossing has gone "through the roof" since Mount Tongariro erupted on Monday night.

Former TVNZ newsreader Judy Bailey says good timing probably saved her from near disaster.

Locals have criticised the response to last night's Tongariro eruption as too slow but authorities have defended their procedures, saying they quickly established there was no immediate risk and put plans in place.

The aviation colour code around Mt Tongariro has been downgraded from red to orange, but the volcanic alert level remains at 2.

Mt Tongariro is one of three major volcanos in the central North Island, sitting alongside mounts Ruapehu and Ngauruhoe.

Mt Tongariro erupted for the first time in over a century at 11.50pm on August 6, 2012, raining ash onto many Central North Island roads and homes.

WeatherWatch.co.nz says today's wind map shows building north to north west winds which should keep the ash around less populated parts of NZ.

Bidders will get the rare chance to secure a piece of New Zealand history when the largest known collection of samples from the famed Pink and White Terraces goes under the hammer.

Four times in the past week, I have put my life in the hands of Air New Zealand's decision to fly under an ash cloud.

Jetstar and Qantas have cancelled all today's flights to, from and within New Zealand.