The Big Island’s weather is greatly influenced by northeast trade winds blowing up against Mauna Kea and Mauna Loa and dumping generous quantities of rain on the wet east side. Not much of this moisture reaches the much drier west side.

On a recent hiking trip to the saddle between Mauna Kea and Mauna Loa, I saw a visual example of what goes on. Cresting a hill, I saw a bank of cloud rolling in from the east. My hike was somewhere under that cloud. When I got closer to that wall of cloud, I could see it fading as it pushed to the west.

My hike started under gray skies, with some light rain, but on this day, the clouds did not keep building. Instead, they burned off somewhat so that it was dry and quite hot by the time I returned to my car, such is the fickle nature of Big Island weather.