Environmental Resource Inventory
Borough of Hawthorne
CLIMATE
INTRODUCTION
The climate of Hawthorne is typical of the Mid-Atlantic region and specifically the New Jersey
Piedmont region. Winters are cold with sub-freezing weather, and summers are hot with
temperatures in the eighties and nineties (Seglin 1975). The difference between winter and
summer averages 40°F, but differences between low and high temperatures can be almost
100°F (Godfrey 1980). Precipitation, in some form, is received throughout the year.
As a result of geography, there are some meteorological occurrences that are unique to
Hawthorne. The First Watchung Ridge (called Orange Mountain by geologists) plays a key role
in Hawthorne’s climate, especially in winter. With an elevation difference of over two hundred
feet between the mountain and the valley there is a marked difference in the texture of winter
precipitation when the temperature is near freezing, with snow accumulating on the mountain
but melting in the valley during winter storms. The First Watchung also alters the local weather
by creating thermal inversions. During nor’Easters (northeastern storms), it is common for
warmer air from the ocean to be brought in by easterly winds. This warm air overrides cold air at
the surface and turns snow into rain, sleet, and freezing rain. The First Watchung has the
capacity to help trap cold air in the valley and extend the duration of an inversion, resulting in
slightly more sleet or freezing rain for those in the valley than in the surrounding areas.
Weather records have been kept for most of the twentieth century for the City of Paterson, and
these can be considered accurate for Hawthorne with some minor adjustments. Along with
Paterson’s records, temperature records were utilized from the NJ State Climatologist Data Site
for northern New Jersey, and temperature data from Newark and Little Falls. Precipitation data
from the rain gauging station at Midland Park was utilized along with the NJ State Climatologist
Data Site for precipitation data.
TEMPERATURE
New Jersey has a humid continental climate typical of the Mid-Atlantic region of the United
States characterized by significant variations between summer and winter temperatures (Seglin
1975). The average temperature differences between summer and winter are approximately
40.7F (State Climatologist 2010) (Fig. 8).
Summer. During the summer, warm tropical air masses move into New Jersey from the south
and southwest.
Many of these moist, hot air masses originate over the Gulf of Mexico, and
flow inland traveling over heated land masses, thereby increasing in temperature prior to
reaching New Jersey. The average July temperature of Paterson, a composite of daily high’s
and lows, is 75.7°F (Ruffner and Bair 1984), while the average northern New Jersey
temperature for July is 73.1°F (N=114) (State Climatologist 2010). The difference in average
July temperatures may be due to the urban character of the City of Paterson. Urbanization in
the City of Paterson contributes to an increase in summer temperatures, as the large amounts
of asphalt and concrete absorb the sun’s energy and act like a heat reservoir, raising
temperatures by several degrees. Summer temperatures in Hawthorne may be slightly lower.
The all-time high temperature for Paterson is 105°F, set on July 10, 1936 (Ludlum 1983).
24
Environmental Resource Inventory
Borough of Hawthorne
80.00
73.1
Average Monthly Temperature (F)
70
60
50
40
30
20
10
71.3
68.2
70.00
63.9
59.5
60.00
53.2
50.00
49
42.8
40.00
38.3
30.00
32.4
29.5
20.0028.5
10.00
0.00
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Month
0
Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
Month
Fig. 8. Mean Monthly Temperature for northern New Jersey. Mean is
based on temperature measurements since 1895 (N=114). Graph
created utilizing State Climatologist Data.
Annual Mean Temperature
Annual Mean Temperature
65
56.0
60
54.0
55
52.0
50.0
50
45
48.0
46.0
44.0
40
7
1
19
9
5
19
9
9
19
8
3
19
7
7
19
7
1
19
6
5
19
6
9
19
5
3
19
4
7
19
4
1
19
3
5
19
3
9
19
2
3
19
1
7
19
1
1
19
0
35
19
0
5
42.0
18
9
The
average
annual
temperature for northern
New Jersey may be
increasing slightly since
1895
(Fig.
9
State
80
Temperature (F)
for Paterson is 31.6°F
(Earthinfo Inc. 1996). The
average temperature for
January in northern New
Jersey is 28.5°F. (N=114)
(State Climatologist 2010),
and again, the difference in
mean temperature may be
related to the urbanization
of the City of Paterson.
The all-time winter low for
the lower Passaic County
area is –16°F set on
February 9, 1934 (Ludlum
1983).
Mean Monthly Temperature
Mean Monthly Temperature
Year
18
95
18
99
19
03
19
07
19
11
19
15
19
19
19
23
19
27
19
31
19
35
19
39
19
43
19
47
19
51
19
55
19
59
19
63
19
67
19
71
19
75
19
79
19
83
19
87
19
91
19
95
19
99
20
03
20
07
Winter. In the wintertime
the prevailing winds are
from
the
northwest,
subjecting Hawthorne to
cold air masses from the
Great Lakes region and
Canada (Earthinfo Inc.
1996). Outpourings of cold
polar airflow east, warmed
slightly in their passage
across the Midwest and
eastern
mountains,
creating
cold
weather
conditions between the
months of November and
March.
In January, the
coldest month of the year,
the average temperature
Year
Fig. 9. Annual Mean Temperature for northern New Jersey.
Climatologist 2010).
The
Graph generated from climatic data from
average annual temperature
NJ
State Climatologist, 1895-2009. (N=114)
in northern New Jersey from
1895-2009 was 50.8°F (N=114), while the average annual temperature in northern New Jersey
from 1970-2009 was 51.3°F (N=39) (State Climatologist 2010).
25
Environmental Resource Inventory
Borough of Hawthorne
PRECIPITATION
Annual
Precipitation
TotalTotal
Annual
Precipitation
7070
6060
5050
40
40
30
30
20
20
18
18 95
918
59
1
891 9
990
1
901 3
39
19 07
0179
11
1
9119
1 15
19 1
1591
1 1 9
91 9
92
19 1 3
23927
1 1
92 93
7 1
19 19
3 35
1
1
1 9
93 3
5 9
1
19 9
3 43
9
1 194
94 7
3
1
19 95
4 1
17
1 95
95 5
11
19 95
51 9
5
1 963
95
199
19 67
619
3
19 71
6179
19 75
719
1
19 79
7159
83
19
7198
9
19 1 7
8399
1 1 1
98 9
79
19 1 5
9 99
1 9
1 2
99 00
5 3
19 20
9 9 07
2
00
3
20
07
10
10
Year
Year
Fig. 10. Mean Annual Precipitation in northern New Jersey. Graph
generated from NJ State Climatologists Office. (1895-2010) (N=114)
Mean Monthly Precipitation
Mean Monthly Precipitation
5
Average Precipitation (inches)
Data
from
the
State
Climatologist
Office
indicates
a
mean
precipitation for northern
New Jersey of 44.60 inches,
in the form of rain, snow,
ice, or sleet pellets, based
on data collected since
1895 (Fig. 10) (State
Climatologist 2010). This is
well above the national
average of 29.14 inches per
year, and higher on average
than many other parts of
New
Jersey
(www.ncdc.noaa.gov).
Precipitation distribution is
fairly even throughout the
year, with approximately 5560 percent of precipitation
occurring during the growing
season
(Godfrey
1980).
Average
monthly
precipitation varies from a
low of 3.13 inches in
February to a high of 4.65
inches in August (Fig. 11)
(State Climatologist 2010).
Both quantity and distribution
contribute
to
amenable
conditions for plant growth.
5
4.5
4.5
4
3.5
4 3
2.5
2
3.5
1.5
1
0.5
3 0
.
.
D
ec
N
ov
.
ct
.
O
pt
Se
g.
Au
Ju
ly
Ju
ne
ay
M
Ap
ril
b
ar
ch
M
Fe
Ja
n
Snow. Snowfall is extremely
variable, and it is possible to
receive anywhere from 2 to
80 inches depending upon
the
year
2.5
(www.ncdc.noaa.gov).
Month
During the 1990’s, there
were two particularly snowy
2
winters: 1993-1994, and
Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Month
1995-1996 with 64.5 and 75
inches of snow, respectively,
recorded at Newark (State
Fig. 11. Mean Monthly Precipitation. Graph generated from NJ State
Climatologist 2010).
Since
Climatologists Office, Historical Precipitation Site. (1895-2010) (N=114)
Hawthorne
experiences
winter temperatures that are
slightly lower than Newark’s, it is reasonable to assume that the total may have been slightly
26
Dec
Environmental Resource Inventory
Borough of Hawthorne
higher. There has been seven winters since 1950 in which more than 50 inches of snow have
fallen: 1957-1958, 1960-1961, 1966-1967, 1977-1978, 1993-1994, 1995-1996, and 2002-2003
(State Climatologist 2010). The average winter season snowfall is 27.2 inches. State
Climatologist 2010), but as little as 1.9 inches fell during the 1972-1973 winter season. Since
1950, there have been three winters with less than 10 inches of snowfall: 1972-1973, 19881989,1997-1998, 2001-2002 (State Climatologist 2010).
Frost. The growing season in Hawthorne averages 174 days between frosts (Dunlap 1978).
The first frost in the fall takes place, on average, around October 27, while the last frost in spring
occurs approximately around April 13 (Dunlap 1978). The heat reservoir effect of the City of
Paterson can inhibit a frost in the immediate surrounding suburban areas of Passaic County.
The frost dates vary from year to year depending upon weather patterns.
WIND
Wind plays an important role on the climate
experienced in Hawthorne. The “Westerlies”
are the dominant wind force experienced in
Hawthorne, and are prime elements directing
this region’s climate.
In this region, the
“Westerlies” are the winds that influence the
weather patterns, moving from west to east.
The “Westerlies” vary in strength, bringing
moist warm air masses from the south in
summer and cool dry air from the north in
winter. The prevailing winds blow from the
northwest (Fig. 12).
Fig. 12. The circular graph plots wind direction
against percent frequency. The concentric
circles within the larger circle denote percents
(0-6%). The petals flow outward from the
center towards the compass point of the origin
of the wind. North represents 0 degrees. The
single line in the chart indicates the mean wind
direction, also pointing to the direction of wind
origin.
The lines teeing off indicate the
standard error (1.37%). Graph generated from
data obtained from Newark Airport (Earthinfo
Inc. 1996).
27
Environmental Resource Inventory
Borough of Hawthorne
STORM EVENTS
Hawthorne has been subjected to almost all types of severe weather, including blizzards,
hurricanes, tornadoes, floods, nor’Easters, and violent thunderstorms. All of these severe
weather occurrences have occurred in Hawthorne at one time or another.
A low-pressure center moving into the area is usually carries moisture-laden air from the Atlantic
Ocean and is indicative of rain. Wind blowing from the east, if sustained, will almost always
bring rain. Although precipitation bearing weather fronts do move east to Hawthorne from the
Great Lakes, it is coastal storms originating in the tropics that lead to the greater precipitation
and wind events (Dunlap 1978).
Tornadoes are rare in New Jersey; Hawthorne was struck by the famous Paterson tornado of
July 1903. A fully developed funnel created a swath of destruction from Lambert Castle into
Hawthorne, damaging 206 buildings and leaving four dead in its wake (Ludlum 1983).
28