Philadelphia weather by month
Philadelphia runs from about 2°C in January to 27°C in July, with August the wettest month at 204 mm.
warmest month
July
27°C
coolest month
January
2°C
wettest month
August
204 mm
worst air month
February
24 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 2°C | 163 mm | 161 h | 13 |
| February | 3°C | 61 mm | 225 h | 24 |
| March | 8°C | 181 mm | 244 h | 11 |
| April | 12°C | 106 mm | 269 h | 10 |
| May | 18°C | 88 mm | 263 h | 11 |
| June | 25°C | 83 mm | 380 h | 12 |
| July | 27°C | 52 mm | 351 h | 14 |
| August | 24°C | 204 mm | 331 h | 16 |
| September | 20°C | 19 mm | 257 h | 14 |
| October | 15°C | 2 mm | 307 h | 8 |
| November | 10°C | 74 mm | 233 h | 12 |
| December | 3°C | 95 mm | 197 h | 13 |
About 3,218 hours of sun a year. Roughly 112 rainy days a year.
These are long-run climate normals, not a forecast. A given year can sit well outside them. PM2.5 is a global model: near the coast it counts sea salt as fine particulate and reads high against ground stations, sometimes by a factor of two. Use the shape of the year, not the absolute number.
where these numbers come from
- · Temperature, rainfall and sunshine: ECMWF ERA5 reanalysis climate normals via Open-Meteo (CC BY 4.0), fetched once and stored.
- · PM2.5: Copernicus CAMS reanalysis, monthly means. Modelled, not station readings; near coasts CAMS counts sea salt as PM2.5 and reads high.
Last reviewed 2026-05-23. Full method, licences and the list of sources we rejected are on the methodology page.