Mauna Kea is a mecca for astronomers because it boasts clear skies more than 300 days a year. That doesn’t mean Mauna Kea doesn’t get rain, just that it falls more on the lower slopes.
This photo shows the access road, a little way below the summit, socked in with clouds and steady rain. It was a little better at the top, but still very cloudy and not a day for seeing stars.