For the second time in two weeks, the National Weather Service has issued blizzard warnings in what might, at first glance, seem to be among the least likely places for such an alert: Hawaii. The warnings were issued Friday, and continued until 6 p.m. HST on Saturday, for the upper reaches of Mauna Kea and Mauna Loa, two volcanic peaks that each rise above 11,000 feet.

As of 4 a.m. HST Saturday, the summit of Mauna Kea was reporting an air temperature of 30 degrees Fahrenheit, with winds gusting to 64 miles per hour, yielding a wind chill index of just 12 degrees Fahrenheit. The warning is for heavy snow with zero visibility, and snow totals of about 1 foot in addition to "much higher drifts." A cold front sweeping across the Hawaiian Islands this weekend is triggering waves of heavy precipitation and high winds, including thunderstorms; the precipitation is falling in the form of snow at higher elevations.

While it is common to see snow on Mauna Loa and Mauna Kea during the summer, two blizzard warnings in the span of two weeks are unusual. The NWS is warning of "life-threatening conditions for anyone attempting to travel to the summits," as winds could gust over 90 miles per hour, which is above hurricane force. To satisfy the official definition of blizzard conditions, visibility has to be below one-quarter mile in heavy snow for at least three hours in a row, with winds of at least 35 miles per hour.

Issuing a blizzard warning for a mountain peak might seem odd, considering most peaks are unoccupied. However, Mauna Loa, which is about 14,000 feet high, is home to weather and astronomy observatories, including the oldest continuously operating monitoring station to keep tabs on the amount of carbon dioxide (a global warming pollutant) in the atmosphere. The data gathered at that laboratory has yielded one of the most iconic graphs in climate science, known as the "Keeling Curve," which shows a recent climb in carbon dioxide levels due to the burning of fossil fuels for energy.

The Keeling Curve of carbon dioxide levels since 1958. Data from long before 1958 shows that current CO2 levels are unprecedented in all of human history. Image: Scripps Institution of Oceanography/Mashable

In 2013, six researchers spent four months living on the slopes of Mauna Loa, investigating what foods astronauts might eat on Mars and during deep-space missions.

Astronomy equipment dots the summit of Mauna Kea, which the University of Hawaii says is home to the "world's largest observatory for optical, infrared, and submillimeter astronomy."

Remarkably, as of 12 p.m. ET on Saturday, Hawaii was one of only two states with a blizzard warning; the other unlucky state is North Dakota, which is more synonymous with cold and snow. Winter storm warnings and advisories were in effect from the Southwest to the Northeast, as a storm pulls out of the Southwest, bringing a mixed bag of wintry precipitation.

The snow in Hawaii is forecast to diminish in intensity by early Saturday afternoon, the NWS said.