September is one of the warmer months of the year in Pittsburgh, with average highs near 25.3°C and lows around 12°C (mean 18.7°C). It is about average for rainfall, averaging 82 mm of rainfall and 71% relative humidity across the period.
September is one of the warmer months of the year in Pittsburgh. Across 45 years of records, the warmest September in Pittsburgh was 2016 — when the month averaged 21.5°C — while the coldest were 1981, 1994 and 2006 at 16.7°C. Typical September days reach 25.3°C with nights near 12°C. The long-term trend is warming, about 0.6°C per decade.
September is about average for rainfall in Pittsburgh, averaging 82 mm of rainfall. The wettest September on record was 2004 with 194 mm, while the driest was 2014 at 22 mm.
Relative humidity in Pittsburgh during September averages 71%. The most humid September was 2018 at 83%, and the least humid was 1985 at 61%.
September receives about 4.2 kWh/m²/day of solar energy in Pittsburgh. The sunniest September was 2007 at 5 kWh/m²/day, and the cloudiest was 1993 at 3.3.
Average wind speed in Pittsburgh during September is 0.2 m/s. The windiest Septembers were 2022, 2023 and 2025, among others at 0.2 m/s, while the calmest was 2024 at 0.1 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 18.0°C | 17.8°C | 18.6°C | 19.6°C | 19.5°C | +1.5°C |
| Avg High | 24.7°C | 24.5°C | 25.3°C | 26.1°C | 26.2°C | +1.5°C |
| Avg Low | 11.3°C | 11.1°C | 11.9°C | 13.0°C | 12.8°C | +1.5°C |
| Avg Rain | 77 mm | 87 mm | 83 mm | 91 mm | 61 mm | -16 mm |
September temperatures in Pittsburgh have risen by about 1.8°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 0.7°C (1989) to a record high of 35.5°C (2011).
Rainfall in September is about average for rainfall, averaging 82 mm, with a wettest year of 194 mm.
One of the best times to visit Pittsburgh
September is one of the best times to visit Pittsburgh. Expect days averaging 25.3°C and nights around 12°C (mean 18.7°C) — warmer than Pittsburgh's yearly average — with higher rainfall (82 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 27.8°C | 20.4°C | 12.9°C | 31.2°C | 6.4°C | 68 mm | 63% | 0.2 m/s | 4.6 |
| 2024 | 27.3°C | 20.4°C | 13.5°C | 31.6°C | 5.9°C | 62 mm | 68% | 0.1 m/s | 4.4 |
| 2023 | 25.9°C | 19.4°C | 12.9°C | 34.0°C | 7.0°C | 36 mm | 71% | 0.2 m/s | 4.4 |
| 2022 | 24.7°C | 18.6°C | 12.6°C | 30.6°C | 4.2°C | 84 mm | 76% | 0.2 m/s | 4 |
| 2021 | 25.5°C | 19.1°C | 12.7°C | 30.6°C | 6.6°C | 80 mm | 75% | 0.2 m/s | 4.4 |
| 2020 | 25.8°C | 18.9°C | 11.9°C | 31.9°C | 2.8°C | 37 mm | 69% | 0.2 m/s | 4.4 |
| 2019 | 28.5°C | 21.4°C | 14.3°C | 33.1°C | 9.1°C | 72 mm | 71% | 0.2 m/s | 4.6 |
| 2018 | 25.8°C | 20.7°C | 15.6°C | 35.3°C | 7.8°C | 191 mm | 83% | 0.2 m/s | 3.5 |
| 2017 | 26.5°C | 19.7°C | 12.8°C | 33.4°C | 5.5°C | 28 mm | 67% | 0.2 m/s | 4.4 |
| 2016 🔥 | 28.7°C | 21.5°C | 14.3°C | 33.5°C | 8.6°C | 76 mm | 67% | 0.2 m/s | 4.7 |
| 2015 | 27.9°C | 21.0°C | 14.2°C | 34.5°C | 7.8°C | 100 mm | 66% | 0.2 m/s | 4.5 |
| 2014 | 25.8°C | 18.6°C | 11.3°C | 32.3°C | 5.0°C | 22 mm | 69% | 0.2 m/s | 4.6 |
| 2013 | 24.7°C | 17.7°C | 10.7°C | 33.3°C | 2.8°C | 46 mm | 71% | 0.2 m/s | 4.4 |
| 2012 | 24.2°C | 17.8°C | 11.3°C | 32.5°C | 4.6°C | 128 mm | 72% | 0.2 m/s | 4 |
| 2011 | 23.5°C | 18.3°C | 13.1°C | 35.5°C | 4.4°C | 145 mm | 83% | 0.2 m/s | 3.5 |
| 2010 | 25.7°C | 18.9°C | 12.2°C | 35.0°C | 8.2°C | 101 mm | 65% | 0.2 m/s | 4.3 |
| 2009 | 24.0°C | 18.0°C | 12.1°C | 29.3°C | 4.3°C | 59 mm | 72% | 0.2 m/s | 3.9 |
| 2008 | 26.2°C | 19.3°C | 12.4°C | 33.7°C | 8.0°C | 74 mm | 68% | 0.2 m/s | 4.3 |
| 2007 | 26.9°C | 19.6°C | 12.2°C | 33.4°C | 4.7°C | 48 mm | 69% | 0.2 m/s | 5 |
| 2006 | 22.0°C | 16.7°C | 11.4°C | 28.6°C | 4.2°C | 110 mm | 78% | 0.2 m/s | 3.5 |
| 2005 | 28.2°C | 20.7°C | 13.2°C | 32.5°C | 4.6°C | 39 mm | 63% | 0.2 m/s | 4.8 |
| 2004 🌧️ | 24.5°C | 18.4°C | 12.4°C | 29.3°C | 5.0°C | 194 mm | 80% | 0.2 m/s | 4.4 |
| 2003 | 23.2°C | 17.4°C | 11.5°C | 27.8°C | 4.8°C | 104 mm | 79% | 0.2 m/s | 3.6 |
| 2002 | 28.1°C | 20.7°C | 13.3°C | 34.8°C | 7.8°C | 81 mm | 63% | 0.2 m/s | 4.6 |
| 2001 | 25.0°C | 17.5°C | 10.1°C | 33.3°C | 3.9°C | 45 mm | 64% | 0.2 m/s | 4.7 |
| 2000 | 24.7°C | 17.7°C | 10.6°C | 33.1°C | 0.9°C | 77 mm | 69% | 0.2 m/s | 4.2 |
| 1999 | 26.4°C | 18.7°C | 11.1°C | 33.5°C | 1.6°C | 56 mm | 62% | 0.2 m/s | 4.3 |
| 1998 | 27.7°C | 20.3°C | 12.8°C | 35.2°C | 5.0°C | 48 mm | 65% | 0.2 m/s | 4.7 |
| 1997 | 23.8°C | 17.2°C | 10.6°C | 29.9°C | 4.6°C | 90 mm | 72% | 0.2 m/s | 4.2 |
| 1996 | 23.1°C | 17.6°C | 12.2°C | 30.5°C | 6.6°C | 146 mm | 79% | 0.2 m/s | 3.5 |
| 1995 | 24.9°C | 17.5°C | 10.2°C | 31.6°C | 1.2°C | 44 mm | 64% | 0.2 m/s | 4.2 |
| 1994 | 23.1°C | 16.7°C | 10.2°C | 30.0°C | 5.0°C | 71 mm | 74% | 0.2 m/s | 4.2 |
| 1993 | 23.7°C | 17.4°C | 11.2°C | 33.2°C | 2.3°C | 105 mm | 72% | 0.2 m/s | 3.3 |
| 1992 | 24.0°C | 17.4°C | 10.8°C | 29.3°C | 1.9°C | 89 mm | 75% | 0.2 m/s | 4.1 |
| 1991 | 25.6°C | 18.3°C | 10.9°C | 33.4°C | 1.8°C | 73 mm | 63% | 0.2 m/s | 4.2 |
| 1990 | 22.7°C | 17.1°C | 11.4°C | 30.1°C | 3.8°C | 150 mm | 80% | 0.2 m/s | 3.7 |
| 1989 | 24.4°C | 17.9°C | 11.4°C | 31.0°C | 0.7°C | 117 mm | 76% | 0.2 m/s | 3.8 |
| 1988 | 24.6°C | 17.5°C | 10.4°C | 30.6°C | 5.8°C | 69 mm | 72% | 0.2 m/s | 4.1 |
| 1987 | 23.3°C | 17.7°C | 12.0°C | 27.0°C | 3.7°C | 114 mm | 79% | 0.2 m/s | 3.8 |
| 1986 | 26.3°C | 19.6°C | 13.0°C | 30.4°C | 3.0°C | 81 mm | 69% | 0.2 m/s | 4.3 |
| 1985 | 26.7°C | 19.1°C | 11.5°C | 32.4°C | 3.1°C | 24 mm | 61% | 0.2 m/s | 4.7 |
| 1984 | 23.8°C | 16.8°C | 9.8°C | 32.0°C | 3.2°C | 38 mm | 69% | 0.2 m/s | 4.5 |
| 1983 | 26.1°C | 18.8°C | 11.4°C | 34.3°C | 2.4°C | 68 mm | 63% | 0.2 m/s | — |
| 1982 | 24.6°C | 17.7°C | 10.8°C | 32.0°C | 4.9°C | 77 mm | 70% | 0.2 m/s | — |
| 1981 ❄️ | 22.4°C | 16.7°C | 11.0°C | 29.1°C | 2.8°C | 105 mm | 76% | 0.2 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 25.3°C with lows near 12°C (mean 18.7°C), based on 45 years of NASA POWER data.
September averages 82 mm of rainfall in Pittsburgh, about average for rainfall. The wettest on record was 194 mm in 2004.
The hottest September reached 35.5°C in 2011. The coldest dipped to 0.7°C in 1989.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.8°C. Daytime highs moved from 24.7°C to 26.2°C and overnight lows from 10.9°C to 12.9°C over the same span.
September is one of the warmer months of the year in Pittsburgh and about average for rainfall, so plan for around 25.3°C daytime highs and 12°C at night.
Not quite — September is the 9th coolest month in Pittsburgh, averaging 18.7°C.
For September in Pittsburgh, pack light layers you can adjust through the day, with typical highs of 25.3°C and lows of 12°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 71% — moderately humid.
Average wind speed in September is 0.2 m/s. The windiest September on record averaged 0.2 m/s (1981).
The wettest September on record was 2004 with 194 mm. On average, September sees 82 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Pittsburgh behaves each September, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for September specifically, along with year-by-year records and how the month has changed over the decades.
