Skadigav

Climate

Template:Climate chart According to the Köppen climate classification, Philadelphia falls under the northern periphery of the humid subtropical climate zone (Köppen Cfa),<ref>Template:Cite web</ref> whereas according to the Trewartha climate classification, the city has a temperate maritime climate (Do) limited to the north by the continental climate (Dc).<ref>Trewartha GT, Horn LH (1980) Introduction to climate, 5th edn. McGraw Hill, New York, NY</ref> Summers are typically hot and muggy, fall and spring are generally mild, and winter is moderately cold. The plant life hardiness zones are 7a and 7b, representing an average annual extreme minimum temperature between Template:Convert.<ref>"USDA Plant Hardiness Zone Map". usda.gov. United States Department of Agriculture. Retrieved December 6, 2017. Note: high resolution map, may be slow to download.</ref>

Snowfall is highly variable with some winters having only light snow while others include major snowstorms. The normal seasonal snowfall averages Template:Convert, with rare snowfalls in November or April, and rarely any sustained snow cover.<ref name="PhillyNOAA"/> Seasonal snowfall accumulation has ranged from trace amounts in 1972–73 to Template:Convert in the winter of 2009–10.<ref name="PhillyNOAA"/>Template:Efn The city's heaviest single-storm snowfall was Template:Convert which occurred in January 1996.<ref>Template:Cite web</ref>

Precipitation is generally spread throughout the year, with eight to eleven wet days per month,<ref>Template:Cite web</ref> at an average annual rate of Template:Convert, but historically ranging from Template:Convert in 1922 to Template:Convert in 2011.<ref name="PhillyNOAA"/> The most rain recorded in one day occurred on July 28, 2013 when Template:Convert fell at Philadelphia International Airport.<ref name="PhillyNOAA"/> Philadelphia has a moderately sunny climate with an average of 2,500 hours of sunshine annually, and a percentage of sunshine ranging from 47% in December to 61% in June, July, and August.<ref name=noaasun-Phily1961/>

The January daily average temperature is Template:Convert,<ref name = "NOAA-txt-Phily1981" /> though the temperature frequently rises to Template:Convert during thaws and dips to Template:Convert for 2 or 3 nights in a normal winter.<ref name = "NOAA-txt-Phily1981" /> July averages Template:Convert,<ref name = "NOAA-txt-Phily1981" /> although heat waves accompanied by high humidity and heat indices are frequent, with highs reaching or exceeding Template:Convert on 27 days of the year. The average window for freezing temperatures is November 6 thru April 2,<ref name="PhillyNOAA"/> allowing a growing season of 217 days. Early fall and late winter are generally dry with February having the lowest average precipitation at Template:Convert. The dewpoint in the summer averages between Template:Convert.<ref name="PhillyNOAA"/>

The highest recorded temperature was Template:Convert on August 7, 1918, but temperatures at or above Template:Convert are not common.<ref name="philadelphia1"/>Template:Efn The lowest officially recorded temperature was Template:Convert on February 9, 1934.<ref name="philadelphia1">Template:Cite web</ref> Temperatures at or below Template:Convert are rare with the last such occurrence being January 19, 1994.<ref name="PhillyNOAA"/> The record low maximum is Template:Convert on February 10, 1899, and December 30, 1880, while the record high minimum is Template:Convert on July 23, 2011, and July 24, 2010.