There is no drinking water at either the Mauna Loa or Observatory trailheads. Both are accessible by one-lane paved roads. Neither has public telephones or public transportation. It takes about an hour to drive from the Kilauea Visitor Center via the Mauna Loa trailhead, and two hours to drive to the Weather Observatory trailhead via Saddle Road. Be prepared for severe winter conditions at any time of the year including blizzards, whiteouts, snow and driving rain.
Temperatures drop below freezing at night.
Do not lose sight of the ahu behind you as you look for the ahu ahead of you, as it is easy to become disorientated. Sunlight is intense, especially with snow cover. Sunglasses and sunscreen are preventive measures against snow blindness and sunburn. The only cure is to descend. Pace yourself, drink plenty of water.