|The Portland Jetport is located 2 3/4 miles west of the site of the
former city office. The surrounding country is mostly open, rolling and
sloping generally toward the Fore River, a body of brackish water about
l,000 feet wide at a distance of about l/2 mile from the station and forming
one boundary (north through east) of the field. The airport is about 5
l/2 miles west–northwest of the open ocean. A slight rise reaching an elevation
of l00 feet, lying northwest of the field, cuts down the wind slightly
from that direction. The older portion of the city is situated on a hill
rising abruptly from sea level to l70 feet, l l/2 miles east of the airport
and on the opposite side of the Fore River. A line of low hills southeast
of the airport, near the ocean, which reach a maximum height of l60 feet,
shuts off sight of the ocean from the airport. Sebago Lake with an area
of 44 square miles is situated about l5 miles to the northwest and 45 miles
farther are the White Mountains, averaging 3,000 to 5,000 feet in height.
As a rule, Portland has very pleasant summers and falls, cold winters with
frequent thaws, and disagreeable springs. Very few summer nights are too
warm and humid for comfortable sleeping. Autumn has the greatest number
of sunny days and the least cloudiness. Winters are quite severe, but begin
late and then extend deeply into the normal springtime. Heavy seasonal
snowfalls, over l00 inches, normally occur about each l0 years. True blizzards
are very rare. The White Mountains, to the northwest, keep considerable
snow from reaching the Portland area and also moderate the temperature.
Normal monthly precipitation is remarkably uniform throughout the year.
Winds are generally quite light with the highest velocities being confined
mostly to March and November. Even in these months the occasional northeasterly
gales have usually lost much of their severity before reaching the coast
of Maine. Temperatures well below zero are recorded frequently each winter.
Cold waves sometimes come in on strong winds, but extremely low temperatures
are generally accompanied by light winds. The average freeze–free season
at the airport station is l39 days. Mid–May is the average occurrence of
the last freeze in spring, and the average occurrence of the first freeze
in fall is late September. The freeze–free period is longer in the city
proper, but may be even shorter at susceptible places further inland. Daily
maximum temperatures at the present airport site agree closely with those
near the former intown office, but minimum temperatures on clear, quiet
mornings range as much as l5 degrees lower at the airport.