The steep grades can result in brake overheating while driving downhill. Driving slowly, and in low gear, will reduce the chances of brake failure. Always use low gear. The first five miles of road are unpaved, have poor traction, narrow sections, blind curves, and rocks on the road. In some places, there may not be enough room for two-way traffic, especially when large trucks are involved.
Slow speeds are essential to avoid road hazards.
Weather Hazards Weather on Mauna Kea can be severe and may include winds over 100 miles per hour, freezing temperatures, and snow storms. Deep snow drifts, freezing fog, and ice on the road can prevent passage. In the winter, ice may form suddenly, without warning. The steep paved grades are dangerous with just a thin coat of ice or snow. Extreme weather that prevents the rescue of trapped visitors can last for more than a week.