September is one of the warmer months of the year in Johnson City, with average highs near 26.9°C and lows around 14°C (mean 20.5°C). It is one of the drier months, averaging 84 mm of rainfall and 68% relative humidity across the period.
September is one of the warmer months of the year in Johnson City. Across 45 years of records, the warmest September in Johnson City was 2019 — when the month averaged 25°C — while the coldest was 1982 at 18.1°C. Typical September days reach 26.9°C with nights near 14°C. The long-term trend is warming, about 0.4°C per decade.
September is one of the drier months in Johnson City, averaging 84 mm of rainfall. The wettest September on record was 2024 with 227 mm, while the driest was 2019 at 10 mm.
Relative humidity in Johnson City during September averages 68%. The most humid September was 1989 at 83%, and the least humid was 1999 at 52%.
September receives about 4.6 kWh/m²/day of solar energy in Johnson City. The sunniest September was 2005 at 5.5 kWh/m²/day, and the cloudiest were 1987, 1988 and 1989 at 4.
Average wind speed in Johnson City during September is 0.9 m/s. The windiest Septembers were 1996, 1999 and 2024 at 1.1 m/s, while the calmest was 2023 at 0.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 19.5°C | 20.5°C | 20.2°C | 21.4°C | 20.7°C | +1.2°C |
| Avg High | 25.9°C | 27.1°C | 26.8°C | 27.6°C | 26.8°C | +0.9°C |
| Avg Low | 13.1°C | 13.8°C | 13.7°C | 15.2°C | 14.5°C | +1.4°C |
| Avg Rain | 90 mm | 66 mm | 88 mm | 81 mm | 107 mm | +17 mm |
September temperatures in Johnson City have risen by about 1.5°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 1.9°C (1983) to a record high of 36°C (2019).
Rainfall in September is one of the drier months, averaging 84 mm, with a wettest year of 227 mm.
One of the best times to visit Johnson City
September is one of the best times to visit Johnson City. Expect days averaging 26.9°C and nights around 14°C (mean 20.5°C) — warmer than Johnson City's yearly average — with higher rainfall (84 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 | 27.0°C | 20.8°C | 14.6°C | 30.8°C | 9.3°C | 94 mm | 69% | 0.8 m/s | 4.8 |
| 2024 🌧️ | 27.7°C | 21.6°C | 15.4°C | 32.7°C | 7.5°C | 227 mm | 69% | 1.1 m/s | 4.5 |
| 2023 | 27.8°C | 21.5°C | 15.2°C | 32.6°C | 10.7°C | 51 mm | 70% | 0.7 m/s | 5 |
| 2022 | 25.9°C | 19.6°C | 13.2°C | 32.9°C | 4.6°C | 98 mm | 71% | 0.9 m/s | 4.8 |
| 2021 | 26.8°C | 20.5°C | 14.3°C | 30.4°C | 8.0°C | 64 mm | 71% | 0.9 m/s | 5 |
| 2020 | 25.7°C | 19.9°C | 14.0°C | 30.6°C | 4.2°C | 111 mm | 76% | 0.9 m/s | 4.4 |
| 2019 🔥 | 32.1°C | 25.0°C | 17.8°C | 36.0°C | 13.9°C | 10 mm | 58% | 0.8 m/s | 5.4 |
| 2018 | 28.7°C | 23.6°C | 18.6°C | 32.7°C | 12.5°C | 131 mm | 77% | 0.9 m/s | 4.2 |
| 2017 | 26.8°C | 20.3°C | 13.9°C | 31.2°C | 8.2°C | 44 mm | 68% | 1 m/s | 4.7 |
| 2016 | 30.2°C | 23.3°C | 16.5°C | 33.7°C | 10.7°C | 49 mm | 61% | 0.9 m/s | 5.3 |
| 2015 | 27.6°C | 21.3°C | 15.1°C | 33.0°C | 9.3°C | 91 mm | 68% | 0.8 m/s | 4.7 |
| 2014 | 26.6°C | 20.6°C | 14.7°C | 31.6°C | 7.4°C | 74 mm | 75% | 0.8 m/s | 4.5 |
| 2013 | 25.3°C | 19.2°C | 13.0°C | 30.0°C | 6.7°C | 67 mm | 76% | 0.8 m/s | 4.7 |
| 2012 | 25.5°C | 19.3°C | 13.1°C | 32.5°C | 3.5°C | 134 mm | 72% | 0.9 m/s | 4.5 |
| 2011 | 25.5°C | 19.9°C | 14.3°C | 35.2°C | 8.1°C | 122 mm | 74% | 0.9 m/s | 4.3 |
| 2010 | 27.8°C | 21.1°C | 14.5°C | 33.1°C | 9.5°C | 85 mm | 65% | 0.9 m/s | 5.1 |
| 2009 | 25.1°C | 19.7°C | 14.4°C | 29.3°C | 6.1°C | 137 mm | 77% | 0.8 m/s | 4.1 |
| 2008 | 27.5°C | 20.8°C | 14.2°C | 32.4°C | 7.3°C | 59 mm | 69% | 0.9 m/s | 4.9 |
| 2007 | 29.8°C | 22.4°C | 15.0°C | 35.1°C | 6.4°C | 39 mm | 58% | 0.8 m/s | 5.2 |
| 2006 | 23.9°C | 18.2°C | 12.4°C | 28.9°C | 5.2°C | 127 mm | 76% | 0.9 m/s | 4.2 |
| 2005 | 30.4°C | 22.6°C | 14.8°C | 33.7°C | 7.3°C | 21 mm | 57% | 1 m/s | 5.5 |
| 2004 | 25.8°C | 19.7°C | 13.6°C | 31.1°C | 6.4°C | 181 mm | 77% | 1 m/s | 4.4 |
| 2003 | 24.7°C | 18.7°C | 12.6°C | 29.1°C | 4.2°C | 92 mm | 75% | 0.9 m/s | 4.9 |
| 2002 | 29.1°C | 22.3°C | 15.4°C | 34.7°C | 11.2°C | 101 mm | 65% | 1 m/s | 4.4 |
| 2001 | 25.1°C | 18.2°C | 11.4°C | 30.5°C | 3.0°C | 58 mm | 65% | 0.9 m/s | 4.8 |
| 2000 | 26.5°C | 19.8°C | 13.0°C | 31.2°C | 3.4°C | 67 mm | 69% | 0.9 m/s | 4.4 |
| 1999 | 28.0°C | 20.4°C | 12.8°C | 33.9°C | 4.9°C | 51 mm | 52% | 1.1 m/s | 5 |
| 1998 | 30.9°C | 23.5°C | 16.0°C | 35.8°C | 7.9°C | 31 mm | 56% | 0.8 m/s | 5.2 |
| 1997 | 27.1°C | 20.2°C | 13.4°C | 33.7°C | 7.5°C | 78 mm | 63% | 0.9 m/s | 4.5 |
| 1996 | 25.3°C | 19.1°C | 13.0°C | 30.0°C | 5.9°C | 104 mm | 72% | 1.1 m/s | 4.3 |
| 1995 | 26.7°C | 20.0°C | 13.3°C | 32.0°C | 7.1°C | 75 mm | 67% | 0.9 m/s | 4.2 |
| 1994 | 25.7°C | 19.1°C | 12.5°C | 31.0°C | 7.2°C | 42 mm | 67% | 0.8 m/s | 4.8 |
| 1993 | 27.3°C | 20.7°C | 14.0°C | 33.5°C | 1.9°C | 80 mm | 65% | 1 m/s | 4.3 |
| 1992 | 26.7°C | 20.5°C | 14.2°C | 31.5°C | 2.5°C | 48 mm | 71% | 0.9 m/s | 4.2 |
| 1991 | 26.1°C | 20.2°C | 14.2°C | 32.9°C | 3.0°C | 81 mm | 70% | 0.8 m/s | 4.1 |
| 1990 | 27.5°C | 20.8°C | 14.2°C | 33.8°C | 3.3°C | 69 mm | 66% | 0.9 m/s | 4.6 |
| 1989 | 23.8°C | 18.7°C | 13.5°C | 28.7°C | 2.6°C | 195 mm | 83% | 0.9 m/s | 4 |
| 1988 | 26.6°C | 20.0°C | 13.5°C | 31.3°C | 6.9°C | 111 mm | 73% | 0.9 m/s | 4 |
| 1987 | 25.9°C | 20.0°C | 14.2°C | 30.7°C | 8.3°C | 115 mm | 69% | 0.9 m/s | 4 |
| 1986 | 26.2°C | 20.6°C | 15.0°C | 29.9°C | 10.4°C | 93 mm | 76% | 0.9 m/s | 4.2 |
| 1985 | 27.4°C | 19.9°C | 12.4°C | 32.5°C | 4.7°C | 20 mm | 61% | 0.8 m/s | 5 |
| 1984 | 26.6°C | 19.3°C | 11.9°C | 33.2°C | 5.3°C | 36 mm | 59% | 0.9 m/s | 4.8 |
| 1983 | 26.5°C | 19.9°C | 13.2°C | 33.9°C | 1.9°C | 52 mm | 62% | 0.9 m/s | — |
| 1982 ❄️ | 23.9°C | 18.1°C | 12.3°C | 28.8°C | 6.1°C | 86 mm | 76% | 0.8 m/s | — |
| 1981 | 26.0°C | 19.2°C | 12.3°C | 32.2°C | 5.1°C | 103 mm | 64% | 0.9 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 26.9°C with lows near 14°C (mean 20.5°C), based on 45 years of NASA POWER data.
September averages 84 mm of rainfall in Johnson City, one of the drier months. The wettest on record was 227 mm in 2024.
The hottest September reached 36°C in 2019. The coldest dipped to 1.9°C in 1983.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.5°C. Daytime highs moved from 26.1°C to 27°C and overnight lows from 12.4°C to 14.5°C over the same span.
September is one of the warmer months of the year in Johnson City and one of the drier months, so plan for around 26.9°C daytime highs and 14°C at night.
Not quite — September is the 9th coolest month in Johnson City, averaging 20.5°C.
For September in Johnson City, pack light layers you can adjust through the day, with typical highs of 26.9°C and lows of 14°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 68% — moderately humid.
Average wind speed in September is 0.9 m/s. The windiest September on record averaged 1.1 m/s (1996).
The wettest September on record was 2024 with 227 mm. On average, September sees 84 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 Johnson City 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.
