New England weather and climate are arguably among the most varied in the world.
It includes extremes of both hot and cold temperatures, droughts, heavy rainfall,
hurricanes, tornadoes, blizzards, and more. These great variations in New England
weather are influenced by many factors relating to the physical geographical setting,
including the regions latitude and coastal orientation.
To understand the dynamic New England climate, it is important to have a basic
understanding of the larger scale general circulation of the atmosphere. Figure
2.1 depicts the surface and upper air flow for the northern hemisphere,
and there is an identical set of cells for the southern hemisphere. The Hadley
Cell to the south primarily controls tropical and subtropical climates,
and only indirectly influences climate in this region. The mid-latitudes, however,
are dominated by westerly circulation at the surface, which is fed by the subsiding
air from the Hadley Cell in the subtropics. These northward-directed winds are
deflected to the right (toward the east) in this hemisphere because of the rotation
of the earth. As a result, the zone of the "westerlies," which are winds that
come from the west and blow toward the east, is created across the middle latitudes.
At the other end of the spectrum, the polar easterlies dominate the very high
latitudes and are made up of extremely cold air that is transported away from
the polar region.
The westerlies and polar easterlies frequently converge between 40o
and 60o North latitude. The boundary between these contrasting air-masses
forms the polar front , which divides
warm and moist air to the south from cold and dry air to the north. The jet
stream resides aloft over this dividing line delineating the location of
the polar front at earths surface. This dynamic boundary generally lies
near New England and the region can fall on either side of the boundary at any
time of the year, thereby shifting us frequently from one air-mass to another.
In winter, the polar front is typically located on the south side of New England
and the region is dominated by colder and drier air-masses from Canada. In summer,
the polar front relocates farther north, placing New England south of the boundary
in warm and more humid air (Figure 2.1
). This is one of the reasons that New England seasons are so distinct. New
England summers are not that dissimilar from locations much farther to the south,
e.g., Miami, Atlanta, or Washington, D.C., because these areas are typically
all imbedded in the same air-mass. These locations can differ greatly in winter,
however, when New England mostly falls on the north side of the polar front.
It is also important to realize that the polar front is always shifting, and
New England can find itself basking in warm and humid air even in winter, but
these incursions are infrequent at that time of year.
There are four important components that dominate New England climate, some
of which relate to the previous discussion. First, the area is located about
halfway between the equator and the north pole, which is why it serves as a
battleground for warm-moist air from the south and cold-dry air from the north.
The surface air-mass boundaries are made up of warm, cold, and stationary fronts,
which frequently traverse the region, bringing us from one air-mass to another
in rapid succession. Second, the region is dominated by a cold water current
along its east coast (coastal Maine, New Hampshire, and eastern Massachusetts)
and a warm water current along the south shore (coastal Connecticut, Rhode Island,
and southern Massachusetts). These currents and corresponding water temperatures
affect summer recreation in the form of swimming comfort and a cooling sea breeze.
Sea breezes are generated by the temperature difference between the cooler water
and warmer land. The sea breeze circulation, particularly along New Englands
east coast, tends to mitigate frequencies and intensities of thunderstorms in
the coastal zone, while bringing relief in the form of mild temperatures in
the peak summer heat. In winter, coastal waters remain warm relative to land
areas, thereby influencing snow-rain boundaries, which are difficult for forecasters
to predict. Third, since New England falls primarily in the zone of the westerlies,
the area is dominated by drier continental airflow from various areas across
North America, rather than having a prevailing flow from off of the Atlantic
Ocean. So, despite the coastal orientation of New England, it does not have
a maritime climate like those
found on the west coast of the United States. Fourth, New England has mountainous
topography which also influences weather patterns. Mountains can enhance precipitation
on the windward side, and create drier conditions on the downwind slopes, known
as the "rainshadow" effect. Increases in elevation also lead to cooler air temperatures.
Figure 2.1 also depicts air-mass characteristics
of New England, based on source regions. As noted, the prevailing wind across
most of New England has a westerly component, while southeast winds are least
common region-wide. However, winds can, and do, come from all directions on
the compass. North and northwest winds deliver to New England cold and dry air
from Canada. Moving counterclockwise, westerly winds transport Canadian air
to the region, but the air is generally modified (warmed slightly) as a result
of passing over the Great Lakes. Southwesterly winds are very common in New
England, but are highly variable in character. These winds can be generated
by a high pressure area in the
mid-Atlantic states, in which the air is Canadian in origin, but has been modified
from the long trajectory over the American Midwest. In this case, the air is
generally cool and dry, but can be hot and dry in summer. However, southwest
winds are also common after the passage of a warm front, which can carry warm
and humid air from the Gulf of Mexico and Caribbean. South and southeast winds
are hot or warm and humid, though these winds have low occurrence rates over
most of New England, with a notable exception along New Englands south
shore. East and northeast winds are cool and humid, as the air takes on the
characteristics of the cooler water of the Labrador current and northern Atlantic
Ocean. Northeast winds in New England are frequently associated with coastal
As a result of New England's position relative to the polar front, its
continental climate type, its coastal orientation, and the mountainous
topography, the regions weather is notorious. It is known for its diversity
over short distances and changability in a matter of minutes. New England has
recorded temperatures up to 107 o F and down to -50o F
(Ludlum, 1976). The high is hotter than the all-time high temperatures ever
recorded in Miami, Florida or Atlanta, Georgia. The low is colder than the record
low temperature in Anchorage, Alaska or International Falls, Minnesota - which
is commonly the coldest location in the conterminous United States. The region
also has rainstorms that rival those in the southeastern United States. As a
result, the splendors of New England weather and its bountiful variety were
noted by many authors ranging from Robert Frost to Mark Twain. Twain captured
the richness of New England weather in his speech at the New England Societys
seventy-first annual dinner in New York:
"Now as to the size of the weather
in New England - lengthways, I mean. It is utterly disproportionate to the
size of that little country. Half the time, when it is packed as full as
it can stick, you will see New England weather sticking out beyond the edges
and projecting around hundreds and hundreds of miles over the neighboring
States. She cant hold a tenth part of her weather"
(Twain, 1935, p. 1110).
Many locations in the United States have the saying " if you dont like
the weather, wait a minute," but nowhere is this more true than in New England.
Yet despite the richness of the weather here, and the abundance of severe weather
types, little research has concentrated on understanding the dynamic climate
of the region.
Ludlum, D. 1976. The Country Journal: New
England Weather Book. Houghton Mifflin: Boston.
Twain, M. 1935. The Family Mark Twain.
Harper and Row: New York.
Dr. Barry Keim, New Hampshire
State Climatologist and Assistant Professor in the Department of Geography and
the Climate Change Research Center in the Institute for the Study of Earth,
Oceans and Space.