Climate of Pennsylvania
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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. Greater Philadelphia lies at the southernmost tip of the Humid continental climate zone, with some characteristics of the Humid subtropical climate that lies in Delaware and Maryland to the south. Moving west toward the mountainous interior of the state, the climate becomes markedly colder, the number of cloudy days increases,[1] and winter snowfall amounts are greater.
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[edit] Temperature
| Monthly Normal High and Low Temperatures For Various Pennsylvania Cities | ||||||||||||
| City | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Scranton | 34/18 | 37/20 | 47/28 | 59/38 | 71/48 | 78/57 | 83/61 | 81/60 | 72/53 | 61/42 | 49/34 | 39/24 |
| Erie | 33/20 | 36/21 | 45/28 | 56/38 | 67/49 | 76/59 | 80/64 | 79/63 | 72/56 | 61/46 | 49/36 | 39/27 |
| Pittsburgh | 37/20 | 39/21 | 50/29 | 62/38 | 71/48 | 80/56 | 85/62 | 83/60 | 76/53 | 64/41 | 53/33 | 42/25 |
| Harrisburg | 38/23 | 41/25 | 51/33 | 63/42 | 73/51 | 81/61 | 86/66 | 84/64 | 76/57 | 64/45 | 53/36 | 42/28 |
| Philadelphia | 39/25 | 42/28 | 51/35 | 62/44 | 72/55 | 81/64 | 86/70 | 84/69 | 77/61 | 66/49 | 55/40 | 44/31 |
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Most interior lowland areas - including most of the major cities - have a moderate humid continental climate (Koppen climate classification Dfa), with hot, humid summers and cool to cold winters. Highland areas in the Appalachians have a more severe humid continental climate (Koppen Dfb), with colder, snowy winters and somewhat cooler summers. The extreme southeastern corner - primarily in the immediate vicinity of Philadelphia - borders on a humid subtropical climate (Koppen Cfa) with somewhat milder winters.
[edit] 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.[2]
[edit] Tropical cyclones
Tropical cyclones threaten the state during the summer and fall, with their main impact being rainfall.[3] 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 [4]. 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.[5]
[edit] See also
[edit] References
- ^ The Pennsylvania State Climatologist. Annual Average Number of Cloudy Days In Pennsylvania. Retrieved on 2008-01-28.
- ^ The Pennsylvania State Climatologist. Climate of Pennsylvania. Retrieved on 2008-01-28.
- ^ David M. Roth. Tropical Cyclone Rainfall for the Mid-Atlantic States. Retrieved on 2008-03-05.
- ^ David M. Roth. Tropical Cyclone Rainfall Maxima. Retrieved on 2008-03-06.
- ^ David M. Roth and Hugh D. Cobb III. RE-ANALYSIS OF THE GALE OF '78 - STORM 9 OF THE 1878 HURRICANE SEASON. Retrieved on 2008-03-05.
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