Barometric Pressure Forecast for Derry, New Hampshire
Barometric pressure forecast for Derry, New Hampshire — in the southern hills between the Merrimack valley and the seacoast, twelve miles south of Manchester. See current barometric pressure and what it means for weather-sensitive people.
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Pressure and weather in Derry
Derry lies on the rolling glacial uplands of Rockingham County, high enough above the Merrimack valley to hold snow longer than Manchester and close enough to the Gulf of Maine that coastal storms reach it with full force. The defining weather is the nor'easter, a low that develops along the mid-Atlantic coast, deepens explosively as it passes the benchmark position southeast of Nantucket and drags Atlantic moisture back over New England. These produce the largest and fastest pressure falls of the year, and the sharpest cases meet the meteorological definition of a bomb. Peak season is January through March, though late autumn storms can be just as deep. Behind each one the wind swings to the northwest and a Canadian high builds in with a rapid pressure rise. Summer is comparatively gentle, with humid stretches broken by afternoon thunderstorms rolling down from the White Mountains, and October is reliably the calmest month.
What this means for you
A rapidly deepening coastal low can drop the barometer further in twelve hours than most weather manages in a week. If nor'easter days line up with your symptoms, the current barometric pressure trend gives you roughly a day of warning.