Climate of Pennsylvania facts for kids
Köppen climate types of Pennsylvania, using 1991-2020 climate normals.
The climate of Pennsylvania is diverse due to the multitude of geographic features found within the state. Straddling two major climate zones, the southeastern corner of Pennsylvania has the warmest climate. A portion of Greater Philadelphia lies at the southernmost tip of the humid continental climate zone, with the city proper being in the humid subtropical climate zone. Still, Philadelphia features colder, snowier winters than most locations with a humid subtropical climate. Moving west toward the mountainous interior of the state, the climate becomes markedly colder, the number of cloudy days increases, and winter snowfall amounts are greater.
Using the January freezing isotherm, the humid subtropical climate (Cfa) only exists in parts of Greater Philadelphia and low-lying areas of the lower Susquehanna Valley from Harrisburg downriver. Pennsylvania's hardiness zone ranges from 5a in high-elevation areas to 7b in parts of Delaware and Philadelphia Counties.
Precipitation
Western areas of the state, particularly cities near Lake Erie, can receive over 100 inches (254 cm) of snowfall annually, and the entire state receives an average of 41 inches (1,041 mm) of rainfall every year. Floods are more common in March and April than other months of the year.
Tropical cyclones
Tropical cyclones normally threaten the states during the summer and fall, with their main impact being rainfall. Although Hurricane Agnes was barely a hurricane at landfall in Florida, its major impact was over the Mid-Atlantic region, where Agnes combined with a non-tropical low to produce widespread rains of 6 inches (150 mm) to 12 inches (300 mm) with local amounts up to 19 inches (480 mm) in western Schuylkill County in Pennsylvania. These rains produced widespread severe flooding from Virginia northward to New York, with other flooding occurring over the western portions of the Carolinas.
Philadelphia has received sustained winds approaching hurricane-force from tropical cyclones in the past.
Climate statistics for selected cities
| Climate data for Allentown, Pennsylvania (Lehigh Valley Int'l), 1981–2010 normals, extremes 1922–present | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °F (°C) | 72 (22) |
77 (25) |
87 (31) |
93 (34) |
97 (36) |
100 (38) |
105 (41) |
100 (38) |
99 (37) |
92 (33) |
81 (27) |
72 (22) |
105 (41) |
| Mean maximum °F (°C) | 57.9 (14.4) |
59.6 (15.3) |
71.6 (22.0) |
82.5 (28.1) |
88.2 (31.2) |
91.9 (33.3) |
94.2 (34.6) |
92.5 (33.6) |
88.0 (31.1) |
79.0 (26.1) |
70.6 (21.4) |
59.7 (15.4) |
95.4 (35.2) |
| Average high °F (°C) | 36.0 (2.2) |
39.8 (4.3) |
49.4 (9.7) |
61.3 (16.3) |
71.5 (21.9) |
80.1 (26.7) |
84.2 (29.0) |
82.4 (28.0) |
74.9 (23.8) |
63.6 (17.6) |
52.5 (11.4) |
40.5 (4.7) |
61.4 (16.3) |
| Average low °F (°C) | 19.5 (−6.9) |
21.7 (−5.7) |
28.8 (−1.8) |
38.5 (3.6) |
48.3 (9.1) |
58.1 (14.5) |
62.7 (17.1) |
60.9 (16.1) |
52.9 (11.6) |
41.3 (5.2) |
32.9 (0.5) |
24.0 (−4.4) |
40.8 (4.9) |
| Mean minimum °F (°C) | 3.0 (−16.1) |
5.7 (−14.6) |
13.1 (−10.5) |
26.0 (−3.3) |
35.5 (1.9) |
46.3 (7.9) |
52.6 (11.4) |
49.8 (9.9) |
39.2 (4.0) |
28.8 (−1.8) |
19.9 (−6.7) |
9.1 (−12.7) |
0.2 (−17.7) |
| Record low °F (°C) | −15 (−26) |
−12 (−24) |
−5 (−21) |
12 (−11) |
28 (−2) |
39 (4) |
46 (8) |
41 (5) |
30 (−1) |
21 (−6) |
3 (−16) |
−8 (−22) |
−15 (−26) |
| Average precipitation inches (mm) | 3.03 (77) |
2.70 (69) |
3.39 (86) |
3.56 (90) |
4.14 (105) |
4.31 (109) |
4.95 (126) |
3.69 (94) |
4.62 (117) |
3.88 (99) |
3.50 (89) |
3.58 (91) |
45.35 (1,152) |
| Average snowfall inches (cm) | 10.0 (25) |
11.1 (28) |
4.9 (12) |
1.0 (2.5) |
0 (0) |
0 (0) |
0 (0) |
0 (0) |
0 (0) |
0 (0) |
0.7 (1.8) |
5.2 (13) |
32.9 (84) |
| Average precipitation days (≥ 0.01 in) | 11.1 | 9.8 | 11.0 | 12.1 | 12.1 | 11.4 | 10.9 | 9.5 | 9.1 | 9.1 | 9.8 | 10.9 | 126.8 |
| Average snowy days (≥ 0.1 in) | 5.6 | 4.8 | 2.5 | 0.4 | 0 | 0 | 0 | 0 | 0 | 0 | 0.6 | 3.5 | 17.4 |
| Average relative humidity (%) | 69.1 | 66.7 | 62.6 | 60.9 | 65.6 | 67.9 | 68.8 | 71.9 | 74.0 | 71.8 | 70.5 | 71.4 | 68.4 |
| Source: NOAA (relative humidity 1961–1990) | |||||||||||||
| Climate data for Harrisburg, Pennsylvania (Harrisburg Int'l), 1981–2010 normals, extremes 1888–present | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °F (°C) | 73 (23) |
78 (26) |
87 (31) |
93 (34) |
97 (36) |
100 (38) |
107 (42) |
104 (40) |
102 (39) |
97 (36) |
84 (29) |
75 (24) |
107 (42) |
| Average high °F (°C) | 37.0 (2.8) |
40.7 (4.8) |
50.4 (10.2) |
62.4 (16.9) |
72.1 (22.3) |
81.0 (27.2) |
85.5 (29.7) |
83.4 (28.6) |
75.6 (24.2) |
64.1 (17.8) |
53.1 (11.7) |
41.3 (5.2) |
62.2 (16.8) |
| Average low °F (°C) | 22.8 (−5.1) |
25.1 (−3.8) |
33.0 (0.6) |
41.9 (5.5) |
52.1 (11.2) |
62.0 (16.7) |
66.3 (19.1) |
64.5 (18.1) |
56.2 (13.4) |
44.6 (7.0) |
35.1 (1.7) |
26.6 (−3.0) |
44.2 (6.8) |
| Record low °F (°C) | −22 (−30) |
−13 (−25) |
−1 (−18) |
11 (−12) |
31 (−1) |
40 (4) |
49 (9) |
45 (7) |
30 (−1) |
23 (−5) |
10 (−12) |
−8 (−22) |
−22 (−30) |
| Average precipitation inches (mm) | 2.88 (73) |
2.39 (61) |
3.37 (86) |
3.10 (79) |
3.79 (96) |
3.60 (91) |
4.61 (117) |
3.20 (81) |
4.07 (103) |
3.27 (83) |
3.23 (82) |
3.23 (82) |
40.74 (1,035) |
| Average snowfall inches (cm) | 8.8 (22) |
10.5 (27) |
5.2 (13) |
0.4 (1.0) |
0 (0) |
0 (0) |
0 (0) |
0 (0) |
0 (0) |
0 (0) |
0.6 (1.5) |
5.1 (13) |
30.6 (78) |
| Average precipitation days (≥ 0.01 in) | 10.6 | 9.9 | 10.9 | 10.8 | 12.2 | 11.1 | 10.7 | 9.1 | 9.2 | 8.8 | 9.0 | 9.7 | 122.0 |
| Average snowy days (≥ 0.1 in) | 5.2 | 5.0 | 2.6 | 0.3 | 0 | 0 | 0 | 0 | 0 | 0 | 0.9 | 2.8 | 16.8 |
| Average relative humidity (%) | 64.4 | 63.2 | 60.7 | 59.2 | 65.2 | 67.7 | 68.6 | 72.2 | 73.8 | 70.5 | 68.2 | 66.4 | 66.7 |
| Mean monthly sunshine hours | 154.9 | 167.2 | 213.8 | 235.7 | 266.7 | 288.5 | 310.1 | 285.4 | 226.7 | 199.2 | 139.6 | 126.0 | 2,613.8 |
| Percent possible sunshine | 52 | 56 | 58 | 59 | 60 | 64 | 68 | 67 | 61 | 58 | 47 | 43 | 59 |
| Source: NOAA (relative humidity and sun 1961–1990 at Capital City Airport) | |||||||||||||
| Climate data for Philadelphia (Philadelphia Airport), 1981–2010 normals, extremes 1872–present | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °F (°C) | 74 (23) |
79 (26) |
87 (31) |
95 (35) |
97 (36) |
102 (39) |
104 (40) |
106 (41) |
102 (39) |
96 (36) |
84 (29) |
73 (23) |
106 (41) |
| Mean maximum °F (°C) | 62.0 (16.7) |
62.7 (17.1) |
73.6 (23.1) |
83.2 (28.4) |
89.1 (31.7) |
94.2 (34.6) |
96.4 (35.8) |
94.7 (34.8) |
89.8 (32.1) |
81.7 (27.6) |
72.3 (22.4) |
63.5 (17.5) |
97.5 (36.4) |
| Average high °F (°C) | 40.3 (4.6) |
43.8 (6.6) |
52.7 (11.5) |
63.9 (17.7) |
73.8 (23.2) |
82.7 (28.2) |
87.1 (30.6) |
85.3 (29.6) |
78.0 (25.6) |
66.6 (19.2) |
56.0 (13.3) |
44.8 (7.1) |
64.6 (18.1) |
| Daily mean °F (°C) | 33.0 (0.6) |
35.7 (2.1) |
43.5 (6.4) |
54.0 (12.2) |
63.9 (17.7) |
73.3 (22.9) |
78.1 (25.6) |
76.6 (24.8) |
69.1 (20.6) |
57.5 (14.2) |
47.6 (8.7) |
37.5 (3.1) |
55.9 (13.3) |
| Average low °F (°C) | 25.6 (−3.6) |
27.7 (−2.4) |
34.4 (1.3) |
44.1 (6.7) |
54.0 (12.2) |
63.8 (17.7) |
69.2 (20.7) |
67.9 (19.9) |
60.3 (15.7) |
48.4 (9.1) |
39.2 (4.0) |
30.1 (−1.1) |
47.1 (8.4) |
| Mean minimum °F (°C) | 8.7 (−12.9) |
12.7 (−10.7) |
19.4 (−7.0) |
31.6 (−0.2) |
42.0 (5.6) |
52.2 (11.2) |
59.8 (15.4) |
57.8 (14.3) |
47.2 (8.4) |
35.8 (2.1) |
26.0 (−3.3) |
15.8 (−9.0) |
6.4 (−14.2) |
| Record low °F (°C) | −7 (−22) |
−11 (−24) |
5 (−15) |
14 (−10) |
28 (−2) |
44 (7) |
51 (11) |
44 (7) |
35 (2) |
25 (−4) |
8 (−13) |
−5 (−21) |
−11 (−24) |
| Average precipitation inches (mm) | 3.03 (77) |
2.65 (67) |
3.79 (96) |
3.56 (90) |
3.71 (94) |
3.43 (87) |
4.35 (110) |
3.50 (89) |
3.78 (96) |
3.18 (81) |
2.99 (76) |
3.56 (90) |
41.53 (1,055) |
| Average snowfall inches (cm) | 6.5 (17) |
8.8 (22) |
2.9 (7.4) |
0.5 (1.3) |
0 (0) |
0 (0) |
0 (0) |
0 (0) |
0 (0) |
0 (0) |
0.3 (0.76) |
3.4 (8.6) |
22.4 (57) |
| Average precipitation days (≥ 0.01 in) | 10.6 | 9.4 | 10.5 | 11.3 | 11.1 | 9.8 | 9.9 | 8.4 | 8.7 | 8.6 | 9.3 | 10.6 | 118.2 |
| Average snowy days (≥ 0.1 in) | 4.4 | 3.6 | 1.8 | 0.4 | 0 | 0 | 0 | 0 | 0 | 0 | 0.2 | 1.8 | 12.2 |
| Average relative humidity (%) | 66.2 | 63.6 | 61.7 | 60.4 | 65.4 | 67.8 | 69.6 | 70.4 | 71.6 | 70.8 | 68.4 | 67.7 | 67.0 |
| Mean monthly sunshine hours | 155.7 | 154.7 | 202.8 | 217.0 | 245.1 | 271.2 | 275.6 | 260.1 | 219.3 | 204.5 | 154.7 | 137.7 | 2,498.4 |
| Percent possible sunshine | 52 | 52 | 55 | 55 | 55 | 61 | 61 | 61 | 59 | 59 | 52 | 47 | 56 |
| Source: NOAA (relative humidity and sun 1961–1990) | |||||||||||||
| Climate data for Pittsburgh (Pittsburgh International Airport), 1981–2010 normals, extremes 1871–present | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °F (°C) | 75 (24) |
77 (25) |
84 (29) |
90 (32) |
95 (35) |
98 (37) |
103 (39) |
103 (39) |
102 (39) |
91 (33) |
82 (28) |
74 (23) |
103 (39) |
| Mean maximum °F (°C) | 59.7 (15.4) |
61.9 (16.6) |
74.9 (23.8) |
81.5 (27.5) |
85.7 (29.8) |
90.0 (32.2) |
91.3 (32.9) |
90.5 (32.5) |
87.2 (30.7) |
79.0 (26.1) |
71.5 (21.9) |
61.3 (16.3) |
92.7 (33.7) |
| Average high °F (°C) | 35.7 (2.1) |
39.3 (4.1) |
49.2 (9.6) |
61.7 (16.5) |
70.8 (21.6) |
79.1 (26.2) |
82.5 (28.1) |
81.4 (27.4) |
74.3 (23.5) |
62.6 (17.0) |
51.2 (10.7) |
39.4 (4.1) |
60.6 (15.9) |
| Average low °F (°C) | 21.1 (−6.1) |
23.0 (−5.0) |
30.0 (−1.1) |
40.2 (4.6) |
49.3 (9.6) |
58.4 (14.7) |
62.8 (17.1) |
61.5 (16.4) |
54.0 (12.2) |
42.9 (6.1) |
34.7 (1.5) |
25.3 (−3.7) |
41.9 (5.5) |
| Mean minimum °F (°C) | −0.1 (−17.8) |
3.6 (−15.8) |
10.9 (−11.7) |
24.6 (−4.1) |
34.8 (1.6) |
44.1 (6.7) |
50.7 (10.4) |
49.6 (9.8) |
39.3 (4.1) |
29.0 (−1.7) |
18.9 (−7.3) |
6.7 (−14.1) |
−3.9 (−19.9) |
| Record low °F (°C) | −22 (−30) |
−20 (−29) |
−5 (−21) |
11 (−12) |
26 (−3) |
34 (1) |
42 (6) |
39 (4) |
31 (−1) |
16 (−9) |
−1 (−18) |
−12 (−24) |
−22 (−30) |
| Average precipitation inches (mm) | 2.70 (69) |
2.39 (61) |
2.95 (75) |
3.11 (79) |
3.95 (100) |
4.30 (109) |
3.83 (97) |
3.48 (88) |
3.11 (79) |
2.29 (58) |
3.23 (82) |
2.85 (72) |
38.19 (970) |
| Average snowfall inches (cm) | 11.5 (29) |
10.2 (26) |
7.4 (19) |
1.5 (3.8) |
0 (0) |
0 (0) |
0 (0) |
0 (0) |
0 (0) |
0.4 (1.0) |
2.1 (5.3) |
8.3 (21) |
41.4 (105) |
| Average precipitation days (≥ 0.01 in) | 16.2 | 13.6 | 14.0 | 13.8 | 13.3 | 12.1 | 10.2 | 9.8 | 9.8 | 10.5 | 12.8 | 15.1 | 151.2 |
| Average snowy days (≥ 0.1 in) | 11.4 | 8.3 | 5.9 | 2.0 | 0 | 0 | 0 | 0 | 0 | 0.3 | 3.0 | 8.5 | 39.4 |
| Average relative humidity (%) | 69.9 | 67.3 | 64.1 | 59.8 | 63.4 | 66.2 | 68.8 | 71.2 | 72.0 | 68.3 | 70.2 | 71.9 | 67.8 |
| Mean monthly sunshine hours | 93.9 | 108.5 | 155.4 | 182.8 | 217.4 | 242.2 | 254.9 | 228.4 | 196.7 | 167.3 | 99.4 | 74.4 | 2,021.3 |
| Percent possible sunshine | 31 | 36 | 42 | 46 | 49 | 54 | 56 | 54 | 53 | 48 | 33 | 26 | 45 |
| Source: NOAA (relative humidity and sun 1961–1990) | |||||||||||||
| Climate data for Wilkes-Barre/Scranton Int'l Airport, Pennsylvania (1981–2010 normals, extremes 1901–present ) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °F (°C) | 69 (21) |
76 (24) |
85 (29) |
93 (34) |
93 (34) |
99 (37) |
103 (39) |
102 (39) |
100 (38) |
91 (33) |
81 (27) |
71 (22) |
103 (39) |
| Mean maximum °F (°C) | 55.4 (13.0) |
56.4 (13.6) |
69.6 (20.9) |
81.3 (27.4) |
86.6 (30.3) |
89.8 (32.1) |
91.8 (33.2) |
90.0 (32.2) |
85.7 (29.8) |
77.3 (25.2) |
68.7 (20.4) |
57.5 (14.2) |
93.4 (34.1) |
| Average high °F (°C) | 33.2 (0.7) |
36.8 (2.7) |
46.2 (7.9) |
59.1 (15.1) |
69.7 (20.9) |
77.7 (25.4) |
81.9 (27.7) |
79.9 (26.6) |
72.3 (22.4) |
60.7 (15.9) |
49.4 (9.7) |
37.5 (3.1) |
58.8 (14.9) |
| Average low °F (°C) | 18.5 (−7.5) |
20.7 (−6.3) |
27.6 (−2.4) |
38.2 (3.4) |
47.6 (8.7) |
56.5 (13.6) |
60.9 (16.1) |
59.5 (15.3) |
52.1 (11.2) |
41.1 (5.1) |
33.3 (0.7) |
23.8 (−4.6) |
40.1 (4.5) |
| Mean minimum °F (°C) | −0.8 (−18.2) |
3.2 (−16.0) |
9.1 (−12.7) |
24.0 (−4.4) |
34.4 (1.3) |
43.1 (6.2) |
49.4 (9.7) |
47.1 (8.4) |
37.5 (3.1) |
28.3 (−2.1) |
18.9 (−7.3) |
5.9 (−14.5) |
−3.1 (−19.5) |
| Record low °F (°C) | −21 (−29) |
−19 (−28) |
−4 (−20) |
8 (−13) |
27 (−3) |
34 (1) |
43 (6) |
38 (3) |
29 (−2) |
19 (−7) |
6 (−14) |
−13 (−25) |
−21 (−29) |
| Average precipitation inches (mm) | 2.37 (60) |
2.03 (52) |
2.55 (65) |
3.33 (85) |
3.52 (89) |
4.03 (102) |
3.79 (96) |
3.41 (87) |
4.07 (103) |
3.34 (85) |
3.14 (80) |
2.68 (68) |
38.26 (972) |
| Average snowfall inches (cm) | 14.2 (36) |
9.3 (24) |
9.0 (23) |
3.3 (8.4) |
0 (0) |
0 (0) |
0 (0) |
0 (0) |
0 (0) |
0.1 (0.25) |
2.9 (7.4) |
7.4 (19) |
46.2 (117) |
| Average precipitation days (≥ 0.01 in) | 12.0 | 11.0 | 11.8 | 12.3 | 13.2 | 12.8 | 11.2 | 11.3 | 10.2 | 10.7 | 11.2 | 11.5 | 139.2 |
| Average snowy days (≥ 0.1 in) | 9.3 | 7.7 | 5.0 | 1.7 | 0 | 0 | 0 | 0 | 0 | 0.1 | 2.1 | 7.1 | 33.0 |
| Average relative humidity (%) | 70.1 | 67.5 | 63.3 | 60.4 | 64.6 | 70.5 | 71.1 | 73.8 | 75.2 | 71.6 | 71.8 | 72.5 | 69.4 |
| Mean monthly sunshine hours | 130.3 | 143.7 | 185.7 | 210.5 | 246.9 | 269.7 | 285.7 | 257.2 | 200.2 | 173.3 | 104.3 | 95.9 | 2,303.4 |
| Percent possible sunshine | 44 | 48 | 50 | 53 | 55 | 60 | 62 | 60 | 54 | 50 | 35 | 33 | 52 |
| Source: NOAA (relative humidity 1964–1990, sun 1961–1990) | |||||||||||||
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Climate of Pennsylvania Facts for Kids. Kiddle Encyclopedia.