| 1961-1990 | 2015-2024 |
|---|
| Hot days a year, 90.1F or hotter | 10.7 | 20 |
|---|
| Days a year at 90F or hotter | 10.8 | 20.5 |
|---|
| Average summer high, F | 82.5 | 84.9 |
|---|
- Of the 19 cities measured, Philadelphia added more hot days than 12.
- Its hottest recent summer was 2024.
Questions
What counts as a hot day in Philadelphia?
90.1F. That was the 90th percentile of a Philadelphia summer day between 1961 and 1990, so it is a local definition rather than a national one. A fixed national threshold would report almost no change in the coolest cities and almost none in the hottest, which is a property of the threshold and not of the weather.
Is this the temperature record at the airport?
No, and it should not be read as one. These are reanalysis values: a model reconstruction on a grid roughly 31 km across, which is consistent over six decades and between cities in a way station records are not. That consistency is what makes the comparison possible, and it is also why a single day here will not match a thermometer reading.
Last updated 2026-08-15.
Sources. ERA5 reanalysis via the Open-Meteo archive, daily maximum 2 m air temperature, for 1961-1990 and 2015-2024.