The average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.
Chance of Clearer Skies
The percentage of time the sky is clear, mostly clear, or partly cloudy (i.e., less than 60% of the sky is covered by clouds).
Daily Chance of Precipitation
The percentage of days in which precipitation is observed, excluding trace quantities.
Average Monthly Rainfall
The average rainfall accumulated over the course of a sliding 31-day period centered on the day in question.
Average Monthly Snowfall
The average liquid-equivalent snowfall accumulated over the course of a sliding 31-day period centered on the day in question.
Hours of Daylight
The number of hours during which the Sun is at least partly above the horizon.
Chance of Muggy Conditions
The percentage of time that is muggy, oppressive, or miserable (i.e., a dew point greater than 65°F).
Average Wind Speed
The average of mean hourly wind speeds at 10 meters above the ground.
The tourism score, which favors clear, rainless days with perceived temperatures between 65°F and 80°F.
The beach/pool score, which favors clear, rainless days with perceived temperatures between 75°F and 90°F.
The percentage chance that a given day is within the growing season, defined 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).
Growing Degree Days
The average growing degree days accumulated over the course of the year, where growing degree days are defined as the integral of warmth above a base temperature (50°F in this case).
Average Water Temperature
The daily average wide-area surface water temperature.
Average Daily Incident Shortwave Solar Energy
The average daily shortwave solar energy reaching the ground per square meter.
This report illustrates the typical weather for Philadelphia International Airport and Chicago, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
The details of the data sources used on this page vary between places and are discussed in detail on each place's dedicated page:
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.