Climate and Average Weather Year Round at Philadelphia International Airport Pennsylvania, United States
At Philadelphia International Airport, the summers are warm, humid, and wet; the winters are very cold and snowy; and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 26°F to 87°F and is rarely below 14°F or above 94°F.
Based on the tourism score, the best times of year to visit Philadelphia International Airport for warm-weather activities are from mid to late June and from early August to late September.
Climate at Philadelphia International Airport
The hot season lasts for 3.5 months, from May 30 to September 16, with an average daily high temperature above 78°F. The hottest month of the year at Philadelphia International Airport is July, with an average high of 87°F and low of 70°F.
The cold season lasts for 3.1 months, from December 2 to March 7, with an average daily high temperature below 50°F. The coldest month of the year at Philadelphia International Airport is January, with an average low of 28°F and high of 41°F.
Average High and Low Temperature at Philadelphia International Airport
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature at Philadelphia International Airport
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
At Philadelphia International Airport, the average percentage of the sky covered by clouds experiences mild seasonal variation over the course of the year.
The clearer part of the year at Philadelphia International Airport begins around June 25 and lasts for 4.6 months, ending around November 14.
The clearest month of the year at Philadelphia International Airport is September, during which on average the sky is clear, mostly clear, or partly cloudy 63% of the time.
The cloudier part of the year begins around November 14 and lasts for 7.4 months, ending around June 25.
The cloudiest month of the year at Philadelphia International Airport is January, during which on average the sky is overcast or mostly cloudy 53% of the time.
Cloud Cover Categories at Philadelphia International Airport
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days at Philadelphia International Airport varies throughout the year.
The wetter season lasts 4.8 months, from April 1 to August 27, with a greater than 30% chance of a given day being a wet day. The month with the most wet days at Philadelphia International Airport is July, with an average of 11.0 days with at least 0.04 inches of precipitation.
The drier season lasts 7.1 months, from August 27 to April 1. The month with the fewest wet days at Philadelphia International Airport is January, with an average of 7.2 days with at least 0.04 inches of precipitation.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone at Philadelphia International Airport is July, with an average of 11.0 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 37% on July 29.
Daily Chance of Precipitation at Philadelphia International Airport
To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Philadelphia International Airport experiences some seasonal variation in monthly rainfall.
Rain falls throughout the year at Philadelphia International Airport. The month with the most rain at Philadelphia International Airport is July, with an average rainfall of 3.6 inches.
The month with the least rain at Philadelphia International Airport is February, with an average rainfall of 2.2 inches.
Average Monthly Rainfall at Philadelphia International Airport
As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Philadelphia International Airport experiences significant seasonal variation in monthly snowfall.
The snowy period of the year lasts for 4.2 months, from November 22 to March 28, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow at Philadelphia International Airport is January, with an average snowfall of 6.1 inches.
The snowless period of the year lasts for 7.8 months, from March 28 to November 22. The least snow falls around July 27, with an average total accumulation of 0.0 inches.
Average Monthly Snowfall at Philadelphia International Airport
The length of the day at Philadelphia International Airport varies significantly over the course of the year. In 2023, the shortest day is December 21, with 9 hours, 20 minutes of daylight; the longest day is June 21, with 15 hours, 0 minutes of daylight.
Hours of Daylight and Twilight at Philadelphia International Airport
The earliest sunrise is at 5:31 AM on June 14, and the latest sunrise is 2 hours, 1 minute later at 7:33 AM on November 4. The earliest sunset is at 4:35 PM on December 8, and the latest sunset is 3 hours, 58 minutes later at 8:33 PM on June 27.
Daylight saving time (DST) is observed at Philadelphia International Airport during 2023, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.
Sunrise & Sunset with Twilight and Daylight Saving Time at Philadelphia International Airport
The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.
Solar Elevation and Azimuth at Philadelphia International Airport
The figure below presents a compact representation of key lunar data for 2023. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.
Moon Rise, Set & Phases at Philadelphia International Airport
We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.
Philadelphia International Airport experiences extreme seasonal variation in the perceived humidity.
The muggier period of the year lasts for 4.0 months, from May 28 to September 27, during which time the comfort level is muggy, oppressive, or miserable at least 15% of the time. The month with the most muggy days at Philadelphia International Airport is July, with 16.9 days that are muggy or worse.
The month with the fewest muggy days at Philadelphia International Airport is February, with 0.0 days that are muggy or worse.
Humidity Comfort Levels at Philadelphia International Airport
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.
The average hourly wind speed at Philadelphia International Airport experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 6.5 months, from October 27 to May 9, with average wind speeds of more than 7.5 miles per hour. The windiest month of the year at Philadelphia International Airport is March, with an average hourly wind speed of 9.2 miles per hour.
The calmer time of year lasts for 5.5 months, from May 9 to October 27. The calmest month of the year at Philadelphia International Airport is August, with an average hourly wind speed of 5.7 miles per hour.
Average Wind Speed at Philadelphia International Airport
The predominant average hourly wind direction at Philadelphia International Airport varies throughout the year.
The wind is most often from the south for 2.6 weeks, from June 10 to June 28 and for 2.5 months, from July 19 to October 3, with a peak percentage of 37% on August 2. The wind is most often from the west for 3.0 weeks, from June 28 to July 19 and for 8.2 months, from October 3 to June 10, with a peak percentage of 37% on July 7.
Wind Direction at Philadelphia International Airport
Philadelphia International Airport is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.
The average water temperature experiences significant seasonal variation over the course of the year.
The time of year with warmer water lasts for 3.5 months, from June 20 to October 3, with an average temperature above 67°F. The month of the year at Philadelphia International Airport with the warmest water is August, with an average temperature of 74°F.
The time of year with cooler water lasts for 3.6 months, from December 22 to April 9, with an average temperature below 46°F. The month of the year at Philadelphia International Airport with the coolest water is February, with an average temperature of 39°F.
Average Water Temperature at Philadelphia International Airport
To characterize how pleasant the weather is at Philadelphia International Airport throughout the year, we compute two travel scores.
The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best times of year to visit Philadelphia International Airport for general outdoor tourist activities are from mid to late June and from early August to late September, with a peak score in the first week of September.
Tourism Score at Philadelphia International Airport
The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Philadelphia International Airport for hot-weather activities is from late June to early September, with a peak score in the last week of July.
Beach/Pool Score at Philadelphia International Airport
For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.
Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.
Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.
Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.
Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.
Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).
The growing season at Philadelphia International Airport typically lasts for 7.5 months (228 days), from around March 31 to around November 14, rarely starting before March 14 or after April 17, and rarely ending before October 26 or after December 7.
Time Spent in Various Temperature Bands and the Growing Season at Philadelphia International Airport
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.
Based on growing degree days alone, the first spring blooms at Philadelphia International Airport should appear around March 30, only rarely appearing before March 14 or after April 14.
Growing Degree Days at Philadelphia International Airport
This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.
The average daily incident shortwave solar energy experiences extreme seasonal variation over the course of the year.
The brighter period of the year lasts for 3.8 months, from April 28 to August 23, with an average daily incident shortwave energy per square meter above 5.9 kWh. The brightest month of the year at Philadelphia International Airport is June, with an average of 6.8 kWh.
The darker period of the year lasts for 3.1 months, from November 6 to February 9, with an average daily incident shortwave energy per square meter below 2.9 kWh. The darkest month of the year at Philadelphia International Airport is December, with an average of 1.9 kWh.
Average Daily Incident Shortwave Solar Energy at Philadelphia International Airport
For the purposes of this report, the geographical coordinates of Philadelphia International Airport are 39.878 deg latitude, -75.240 deg longitude, and 3 ft elevation.
The topography within 2 miles of Philadelphia International Airport is essentially flat, with a maximum elevation change of 85 feet and an average elevation above sea level of 8 feet. Within 10 miles is essentially flat (436 feet). Within 50 miles contains only modest variations in elevation (1,250 feet).
The area within 2 miles of Philadelphia International Airport is covered by artificial surfaces (90%) and water (10%), within 10 miles by artificial surfaces (77%), and within 50 miles by trees (39%) and cropland (27%).
This report illustrates the typical weather at Philadelphia International Airport, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
Philadelphia International Airport has a weather station that reported reliably enough during the analysis period that we have included it in our network. When available, historical temperature and dew point measurements are taken directly from this weather station. These records are obtained from NOAA's Integrated Surface Hourly data set, falling back on ICAO METAR records as required.
In the case of missing or erroneous measurements from this station, we fall back on records from nearby stations, adjusted according to typical seasonal and diurnal intra-station differences. For a given day of the year and hour of the day, the fallback station is selected to minimize the prediction error over the years for which there are measurements for both stations.
The stations on which we may fall back include but are not limited to Wings Field; North Philadelphia Airport; Willow Grove, Naval Air Station; South Jersey Regional Airport; New Castle Airport; Doylestown Airport; Pottstown Limerick Airport; and Millville Municipal Airport.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for airports and weather stations are provided by AskGeo.com .
Maps are © OpenStreetMap contributors.
The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.
We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.
We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.
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