Here you see the view of the western mountains of Mount Desert Island, Maine’s largest island, as seen from the edge of a greening field on Amen Ridge in Brooklin. Daffodils are all the flowers that the field offers now, but it will be full of blooming lupines next month. Blue Hill and Jericho Bays appear gray because the day was “Mostly Cloudy,” according to the weather tellers.
I’ve always wondered whether such weather descriptions had some uniform science behind them. Well, it turns out that they do: accepted definitions for these terms have been issued by the National Weather Service, which divides the sky in eighths (“oktas”) for world-wide standardization:
“Overcast” or “Cloudy” means 7/8 to 8/8 cloud cover;
“Mostly Cloudy,” as you see here, is when there is 5/8 to 7/8 cloud cover;
“Partly Cloudy” or “Partly Sunny” means 3/8 to 5/8 cloud cover;
“Mostly Sunny” or “Mostly Clear” mean 1/8 to 3/8 cloud cover, and
“Sunny” or “Clear” mean 1/8 or less cloud cover.
(Image taken in Brooklin, Maine, on May 12, 2026.) Click on the image to enlarge it.