Temperatures drop below freezing at night. Do not lose sight of the ahu behind you and you look for the ahu ahead, as it is easy to become disoriented. Sunlight is intense, especially with snow cover. Pace yourself as you ascend Mauna Loa, and be prepared for rigorous conditions. Altitude sickness is common there, so be ready for the necessity of moving back to lower elevations.
Eruptions are possible at any time.
Always stay upslope from active lava flows and remain on higher ground. Stay upwind of volcanic gases. Persons with breathing problems, heart difficulties, pregnant women, infants and young children are especially at risk around volcanic fumes. They contain hydrochloric acid, sulfur dioxide and particulate matter. Other hazards include steam explosions where lava enters the ocean.