Barometric Pressure Forecast for South Portland, Maine
Barometric pressure forecast for South Portland, Maine — on Casco Bay across the Fore River from Portland. See current barometric pressure and what it means for weather-sensitive people.
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Pressure and weather in South Portland
South Portland faces Casco Bay from the south side of the Fore River, and it sits directly in the path of the storm track's most explosive stretch. Lows moving up the eastern seaboard reach their deepest point over the Gulf of Maine, and the waters offshore are one of the world's more reliable places for rapid cyclogenesis — pressure falls of more than 24 millibars in 24 hours are recorded here several times most winters. Those are the storms that bury the coast in snow and produce the biggest single-day barometric swings anywhere in New England. The Gulf of Maine also keeps the water cold year round, so summer brings dense sea fog rolling in on southerly flow with almost no pressure change at all, which is a useful contrast for anyone trying to separate humidity effects from pressure effects. December through March is the period to watch closely.
What this means for you
Few places give you a cleaner natural experiment: winter storms deliver huge pressure drops, summer fog delivers high humidity with none. Track both in Pressure Pal and the comparison will tell you fairly quickly whether barometric pressure headaches or humidity is the stronger driver for you.