As the season officially shifted to fall last week, so too did the winds. The gentle Southerly summer breezes swung around and came from the North. They were cooler, dryer and more intense, rattling the drying leaves and signifying the shift in season. Anecdotally, it seems like it gets windier in the fall. But, I wondered whether this was really the case. I did a little research and came upon a treasure trove of statistics on Weather Spark — everything from solar radiation to water temperature to — wind. According to their numbers, the windiest weather in Maine begins on October 14th and lasts until April 19th. So, last week was technically a bit early, but not too far off.

These averages, however, are for the entire state including both coastal and inland areas. The variation from one “habitat” to the other can be quite extreme. And, the factors that influence wind are also quite different. The coastal part is what is of most interest for me, so I’ll try to tackle that here. Probably the most familiar breeze associated with the coast is the daily sea breeze. This is when the wind blows off the water towards the land. For that reason, it is also called an onshore breeze. This happens because of a difference in pressure between the water and the land — a difference created by the higher capacity of land to absorb heat. Since hot air rises, it creates a vacuum underneath it, pulling cooler air off the water towards the people sitting on the shore. The opposite is true after sunset when the land cools and the water holds its heat longer. The warmer air over the water does the same thing that happened on land — it rises and sucks the air from the land out towards sea creating and offshore breeze.

These are daily shifts, which may seem different than seasonal shifts. But, the same principles apply. It has something to do with high and low pressure (MORE). In the summer months, there is a high-pressure system, known as the Bermuda High that sits off the East coast. The air moves clockwise around the center of this system, pulling in warm, moist air from the south and flinging it up towards Maine. It also brings in mist and fog as the warm air meets the cool Maine water. These predominantly southern summer breezes are not only pleasant, but also serve a functional purpose. In the past, when much travel happened under sail, these breezes were particularly helpful in carrying ships up towards Maine. In the winter, the situation reverses and the low-pressure system pulls cold air down from Canada, bringing us the famed Nor’easter storms full of wind and snow.

Characterizing winds as being Northerly or Southerly grossly exaggerates the regularity of their direction. In reality, there are fine gradations of wind direction. Throughout history, these have been illustrated on a compass rose. They are sometimes named simply by their cardinal direction — Northwest, Northeast, and so forth. They also have names derived from ancient stories and mythology. The Greeks refer to the Anemoi — the four major winds: Boreas (north), Zephyrus (west), Notus (south), Eurus (east). Homer mentions these winds in The Odyssey. And they are depicted as winged men on the Tower of Winds in Athens, Greece.

You can very easily go down a rabbit hole of names for winds. There are winds that are specific to many places in the world. These are not necessarily named for direction, but instead are often named for the conditions they bring or the locations where they originate – the scirocco that comes from North African and blows over Europe; the mistral that blows storms over France; and the famously hot and dry Santa Ana that blows through the canyons of Los Angeles. If you are really interested in learning the innumerable number of winds, you can check out Bowditch’s The American Practical Navigator, in which winds take up a big chunk of the chapter on weather elements.

Whatever the wind and whatever the direction, there is a power that wind exerts over the landscape of coastal Maine. It brings change, whether from a hot day to a cool night, or from a moist summer to a crisp fall. We notice it above water and the world atop and beneath the water notices it as well as temperatures shift and a new season begins.

Comments are not available on this story.

filed under: