In the western US, weather varies with altitude, not latitude. Within 45 minutes of downtown Tucson, AZ (el 2,500) you can reach a ski resort (elev 85,00) in the Santa Catalina Mountains. So at 13,000 feet in Hawaii, it can be winter.

What surprises me is the apparently flaccid SAR response by the NPS, especially since the hiker had registered. More information night clear up this - the usual cautions about drawing conclusions from second hand, sketchy media reports apply here.