September is one of the warmer months of the year in Grand Junction, with average highs near 25.4°C and lows around 9.8°C (mean 17.6°C). It is about average for rainfall, averaging 39 mm of rainfall and 42% relative humidity across the period.
September is one of the warmer months of the year in Grand Junction. Across 45 years of records, the warmest September in Grand Junction was 2022 — when the month averaged 20.2°C — while the coldest was 1985 at 14.1°C. Typical September days reach 25.4°C with nights near 9.8°C. The long-term trend is warming, about 0.6°C per decade.
September is about average for rainfall in Grand Junction, averaging 39 mm of rainfall. The wettest September on record was 1997 with 90 mm, while the driest was 2018 at 5 mm.
Relative humidity in Grand Junction during September averages 42%. The most humid September was 1997 at 57%, and the least humid was 2001 at 30%.
September receives about 5.5 kWh/m²/day of solar energy in Grand Junction. The sunniest September was 2010 at 6.2 kWh/m²/day, and the cloudiest was 1986 at 4.6.
Average wind speed in Grand Junction during September is 2.1 m/s. The windiest September was 1986 at 2.9 m/s, while the calmest was 1990 at 1.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 16.4°C | 17.2°C | 17.2°C | 18.5°C | 18.9°C | +2.5°C |
| Avg High | 24.3°C | 24.9°C | 25.1°C | 26.2°C | 26.9°C | +2.6°C |
| Avg Low | 8.6°C | 9.5°C | 9.3°C | 10.8°C | 11.0°C | +2.4°C |
| Avg Rain | 40 mm | 41 mm | 47 mm | 35 mm | 28 mm | -12 mm |
September temperatures in Grand Junction have risen by about 2.5°C between 1981–1985 and 2021–2025.
September has ranged from a record low of -4.5°C (1996) to a record high of 36.4°C (2022).
Rainfall in September is about average for rainfall, averaging 39 mm, with a wettest year of 90 mm.
One of the best times to visit Grand Junction
September is one of the best times to visit Grand Junction. Expect days averaging 25.4°C and nights around 9.8°C (mean 17.6°C) — warmer than Grand Junction's yearly average — with moderate rainfall (39 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 | 25.6°C | 18.1°C | 10.7°C | 31.4°C | 5.5°C | 32 mm | 49% | 1.8 m/s | 5.1 |
| 2024 | 27.8°C | 19.6°C | 11.3°C | 30.7°C | 6.0°C | 16 mm | 41% | 2 m/s | 5.6 |
| 2023 | 26.3°C | 18.7°C | 11.0°C | 31.0°C | 7.2°C | 10 mm | 36% | 2.1 m/s | 5.6 |
| 2022 🔥 | 28.2°C | 20.2°C | 12.1°C | 36.4°C | 7.4°C | 47 mm | 41% | 1.9 m/s | 5.5 |
| 2021 | 27.0°C | 19.1°C | 11.2°C | 33.2°C | 3.4°C | 41 mm | 40% | 1.9 m/s | 5.6 |
| 2020 | 26.2°C | 17.9°C | 9.7°C | 35.1°C | 2.0°C | 23 mm | 35% | 1.8 m/s | 5.7 |
| 2019 | 27.3°C | 19.6°C | 12.0°C | 36.1°C | 5.5°C | 12 mm | 34% | 2.8 m/s | 5.7 |
| 2018 | 27.7°C | 19.6°C | 11.5°C | 31.8°C | 5.4°C | 5 mm | 34% | 2.3 m/s | 5.9 |
| 2017 | 25.2°C | 17.8°C | 10.4°C | 34.9°C | 0.1°C | 38 mm | 43% | 2.2 m/s | 5.3 |
| 2016 | 24.9°C | 17.3°C | 9.7°C | 30.6°C | 2.2°C | 35 mm | 40% | 2.5 m/s | 5.4 |
| 2015 | 27.0°C | 19.4°C | 11.7°C | 31.1°C | 7.2°C | 26 mm | 41% | 2 m/s | 5.5 |
| 2014 | 25.9°C | 18.4°C | 11.0°C | 30.5°C | 3.3°C | 69 mm | 51% | 1.8 m/s | 5.4 |
| 2013 | 24.7°C | 17.5°C | 10.3°C | 33.7°C | 0.1°C | 85 mm | 54% | 2.2 m/s | 5 |
| 2012 | 26.4°C | 18.5°C | 10.7°C | 31.8°C | 5.7°C | 22 mm | 39% | 1.8 m/s | 5.5 |
| 2011 | 25.9°C | 18.2°C | 10.5°C | 32.6°C | 7.4°C | 31 mm | 43% | 1.8 m/s | 5.6 |
| 2010 | 27.3°C | 18.6°C | 9.8°C | 32.2°C | 5.7°C | 23 mm | 33% | 2.2 m/s | 6.2 |
| 2009 | 25.7°C | 18.0°C | 10.4°C | 31.9°C | 1.0°C | 24 mm | 41% | 2.1 m/s | 5.4 |
| 2008 | 25.5°C | 17.2°C | 9.0°C | 29.0°C | 3.5°C | 17 mm | 36% | 1.9 m/s | 5.7 |
| 2007 | 25.4°C | 17.6°C | 9.7°C | 33.0°C | -0.7°C | 73 mm | 41% | 2.4 m/s | 5.6 |
| 2006 | 21.9°C | 14.4°C | 7.0°C | 30.7°C | -1.1°C | 70 mm | 46% | 1.9 m/s | 5.2 |
| 2005 | 25.2°C | 17.5°C | 9.9°C | 31.3°C | 5.4°C | 62 mm | 44% | 2.2 m/s | 5.6 |
| 2004 | 23.7°C | 16.1°C | 8.5°C | 32.1°C | 0.0°C | 73 mm | 45% | 2.3 m/s | 5.2 |
| 2003 | 25.2°C | 17.0°C | 8.8°C | 31.0°C | 0.3°C | 39 mm | 38% | 2 m/s | 5.7 |
| 2002 | 24.2°C | 16.8°C | 9.5°C | 32.1°C | 3.8°C | 65 mm | 49% | 2.1 m/s | 5.1 |
| 2001 | 28.0°C | 19.6°C | 11.2°C | 32.6°C | 2.4°C | 13 mm | 30% | 2 m/s | 5.8 |
| 2000 | 26.0°C | 17.6°C | 9.2°C | 32.5°C | -3.0°C | 37 mm | 41% | 2.5 m/s | 5.5 |
| 1999 | 23.2°C | 15.4°C | 7.6°C | 28.7°C | -2.5°C | 29 mm | 44% | 1.9 m/s | 5.6 |
| 1998 | 26.9°C | 19.2°C | 11.6°C | 32.8°C | 6.4°C | 26 mm | 42% | 2 m/s | 5.5 |
| 1997 🌧️ | 24.7°C | 17.6°C | 10.6°C | 29.5°C | 3.1°C | 90 mm | 57% | 2 m/s | 5.1 |
| 1996 | 22.4°C | 14.9°C | 7.3°C | 32.3°C | -4.5°C | 58 mm | 48% | 1.9 m/s | 5 |
| 1995 | 24.9°C | 17.3°C | 9.7°C | 34.7°C | 0.2°C | 46 mm | 41% | 2.1 m/s | 5.5 |
| 1994 | 25.8°C | 18.1°C | 10.5°C | 30.6°C | 3.2°C | 44 mm | 40% | 2.2 m/s | 5.5 |
| 1993 | 24.9°C | 16.3°C | 7.8°C | 29.9°C | 1.3°C | 18 mm | 35% | 2.3 m/s | 5.8 |
| 1992 | 25.5°C | 17.5°C | 9.6°C | 29.3°C | 3.5°C | 15 mm | 35% | 2.2 m/s | 5.5 |
| 1991 | 24.0°C | 16.3°C | 8.7°C | 31.1°C | 2.9°C | 41 mm | 48% | 2.1 m/s | 5.5 |
| 1990 | 26.5°C | 18.9°C | 11.3°C | 33.0°C | 5.1°C | 38 mm | 47% | 1.7 m/s | 5.2 |
| 1989 | 25.8°C | 17.2°C | 8.6°C | 30.0°C | 2.8°C | 15 mm | 33% | 2.4 m/s | 5.8 |
| 1988 | 24.1°C | 15.7°C | 7.4°C | 32.6°C | -0.6°C | 47 mm | 42% | 2.3 m/s | 5.5 |
| 1987 | 25.5°C | 17.1°C | 8.6°C | 30.9°C | 4.8°C | 10 mm | 36% | 1.8 m/s | 5.7 |
| 1986 | 21.4°C | 14.6°C | 7.9°C | 30.3°C | 0.0°C | 75 mm | 48% | 2.9 m/s | 4.6 |
| 1985 ❄️ | 21.9°C | 14.1°C | 6.4°C | 30.3°C | -4.1°C | 59 mm | 46% | 2.7 m/s | 5.2 |
| 1984 | 24.9°C | 16.8°C | 8.7°C | 31.5°C | -0.2°C | 25 mm | 44% | 2.4 m/s | 5.4 |
| 1983 | 26.2°C | 18.3°C | 10.4°C | 31.9°C | 0.0°C | 26 mm | 39% | 2.3 m/s | — |
| 1982 | 22.8°C | 15.9°C | 9.1°C | 30.9°C | 1.3°C | 81 mm | 55% | 2.4 m/s | — |
| 1981 | 25.8°C | 18.0°C | 10.2°C | 30.2°C | 6.8°C | 24 mm | 45% | 2.1 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 25.4°C with lows near 9.8°C (mean 17.6°C), based on 45 years of NASA POWER data.
September averages 39 mm of rainfall in Grand Junction, about average for rainfall. The wettest on record was 90 mm in 1997.
The hottest September reached 36.4°C in 2022. The coldest dipped to -4.5°C in 1996.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 2.5°C. Daytime highs moved from 24.3°C to 27°C and overnight lows from 9°C to 11.3°C over the same span.
September is one of the warmer months of the year in Grand Junction and about average for rainfall, so plan for around 25.4°C daytime highs and 9.8°C at night.
Not quite — September is the 9th coolest month in Grand Junction, averaging 17.6°C.
For September in Grand Junction, pack light layers you can adjust through the day, with typical highs of 25.4°C and lows of 9.8°C.
Relative humidity in September averages 42% — relatively dry.
Average wind speed in September is 2.1 m/s. The windiest September on record averaged 2.9 m/s (1986).
The wettest September on record was 1997 with 90 mm. On average, September sees 39 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 Grand Junction 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.
