The forecast snap of cold weather will cause further rescues on the Tongariro Alpine Crossing if visitors don't prepare or plan their hiking trips, says police.

In the last two weeks, Police and LandSAR in the Central North Island have rescued numerous people off Mt Tongariro.

Police are concerned that some people do not understand the weather risks associated with hiking in an alpine environment.

The forecast for this week includes snow down to 700m, which means it will be extremely cold in the mountains and there is a high risk of hypothermia if ill prepared.

Last weekend two people were rescued and the previous weekend nine people were rescued within Tongariro National Park.

One of the rescues was a group of six adults and a two-year-old child.

When found some of them were suffering from hypothermia, and rescuers thought they would have died if we did not get to them.

The Tongariro Alpine Crossing is not a casual walk in the park - it is an alpine crossing in a volcanic environment that requires a high level of fitness and understanding of weather conditions.

'You need to plan and prepare for alpine hikes,” stresses Senior Constables Barry Shepherd of Taupo and Conrad Smith of National Park Police.

'If the weather is not favourable, do another activity, don't risk your life."

'If it's raining and cloudy down low, it is likely that the scenic views will be obstructed, and it will be wetter and even colder at altitude – it's not fun hiking in cold wet conditions and there are often much safer and still enjoyable alternatives, which can be recommended by i-site or DOC visitor centres."

The summer season for hiking the Tongariro Alpine Crossing ends this month as the increased frequency of snow will bring avalanches and hazardous icy conditions.

The Department of Conservation will be recommending visitors go with a guide in the winter season.

In winter conditions, hikers need knowledge and experience of how to operate in the alpine environment, including; the ability to use an ice axe, crampons, and an understanding of the risks associated with travelling in alpine terrain, to keep themselves alive.

The Tongariro Alpine Crossing attracts people from all over the world and is a memorable achievement however local Iwi, Police, LandSAR, Department of Conservation encourage people to attempt the 19km Alpine Crossing with some thought, preparation and respect, so it's memorable for all the right reasons.