Further cold weather is planned so the constables are urging trampers to keep tabs on ever-changing weather conditions.
"You need to plan and prepare for alpine hikes.
"If the weather is not favourable, do another activity, don't risk your life."
Some people did not understand the weather risks associated with hiking in an alpine environment, they said.
"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.
"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 winter visitors go with a guide.