September is one of the warmer months of the year in Yakima, with average highs near 22.7°C and lows around 8.9°C (mean 15.8°C). It is one of the drier months, averaging 21 mm of rainfall and 56% relative humidity across the period.
September is one of the warmer months of the year in Yakima. Across 45 years of records, the warmest September in Yakima was 2022 — when the month averaged 18.4°C — while the coldest was 1985 at 11.7°C. Typical September days reach 22.7°C with nights near 8.9°C. The long-term trend is warming, about 0.6°C per decade.
September is one of the drier months in Yakima, averaging 21 mm of rainfall. The wettest September on record was 2013 with 71 mm, while the driest was 2012 at 1 mm.
Relative humidity in Yakima during September averages 56%. The most humid September was 2010 at 67%, and the least humid was 2012 at 47%.
September receives about 4.6 kWh/m²/day of solar energy in Yakima. The sunniest September was 1999 at 5.3 kWh/m²/day, and the cloudiest was 2019 at 3.9.
Average wind speed in Yakima during September is 1.5 m/s. The windiest Septembers were 2007, 2009 and 2013, among others at 1.7 m/s, while the calmest was 2012 at 1.3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 14.0°C | 16.0°C | 15.9°C | 16.0°C | 17.4°C | +3.4°C |
| Avg High | 20.7°C | 23.1°C | 23.0°C | 22.6°C | 24.5°C | +3.8°C |
| Avg Low | 7.3°C | 9.0°C | 8.8°C | 9.3°C | 10.3°C | +3°C |
| Avg Rain | 34 mm | 19 mm | 14 mm | 21 mm | 16 mm | -19 mm |
September temperatures in Yakima have risen by about 4°C between 1981–1985 and 2021–2025.
September has ranged from a record low of -0.9°C (2019) to a record high of 35.4°C (2017).
Rainfall in September is one of the drier months, averaging 21 mm, with a wettest year of 71 mm.
One of the best times to visit Yakima
September is one of the best times to visit Yakima. Expect days averaging 22.7°C and nights around 8.9°C (mean 15.8°C) — warmer than Yakima's yearly average — with low rainfall (21 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 | 25.2°C | 18.1°C | 11.0°C | 34.5°C | 3.3°C | 13 mm | 57% | 1.5 m/s | 4.5 |
| 2024 | 24.3°C | 17.1°C | 9.9°C | 34.2°C | 1.1°C | 7 mm | 55% | 1.6 m/s | 4.6 |
| 2023 | 22.7°C | 16.2°C | 9.7°C | 31.5°C | 3.4°C | 22 mm | 56% | 1.5 m/s | 4.3 |
| 2022 🔥 | 25.6°C | 18.4°C | 11.1°C | 34.2°C | 6.8°C | 8 mm | 48% | 1.5 m/s | 4.7 |
| 2021 | 23.5°C | 16.4°C | 9.2°C | 30.3°C | 4.0°C | 27 mm | 53% | 1.5 m/s | 4.4 |
| 2020 | 25.4°C | 18.2°C | 11.1°C | 33.8°C | 5.6°C | 18 mm | 50% | 1.6 m/s | 4.1 |
| 2019 | 20.7°C | 14.9°C | 9.1°C | 29.8°C | -0.9°C | 25 mm | 65% | 1.5 m/s | 3.9 |
| 2018 | 21.9°C | 15.0°C | 8.1°C | 29.4°C | 3.5°C | 4 mm | 54% | 1.4 m/s | 4.8 |
| 2017 | 23.0°C | 16.8°C | 10.6°C | 35.4°C | 4.3°C | 17 mm | 56% | 1.4 m/s | 4.1 |
| 2016 | 21.7°C | 14.9°C | 8.1°C | 28.8°C | 4.2°C | 11 mm | 57% | 1.5 m/s | 4.7 |
| 2015 | 22.1°C | 15.1°C | 8.1°C | 34.3°C | 2.8°C | 6 mm | 54% | 1.4 m/s | 4.6 |
| 2014 | 23.2°C | 16.4°C | 9.6°C | 30.5°C | 4.0°C | 21 mm | 55% | 1.6 m/s | 4.7 |
| 2013 🌧️ | 22.4°C | 16.5°C | 10.5°C | 32.5°C | 4.5°C | 71 mm | 64% | 1.7 m/s | 4.1 |
| 2012 | 25.0°C | 17.4°C | 9.8°C | 31.2°C | 3.6°C | 1 mm | 47% | 1.3 m/s | 5.1 |
| 2011 | 25.1°C | 17.9°C | 10.7°C | 33.7°C | 3.8°C | 7 mm | 50% | 1.5 m/s | 4.8 |
| 2010 | 21.2°C | 15.0°C | 8.8°C | 29.3°C | 4.4°C | 41 mm | 67% | 1.4 m/s | 4.2 |
| 2009 | 24.0°C | 16.8°C | 9.5°C | 32.5°C | 2.1°C | 15 mm | 51% | 1.7 m/s | 4.8 |
| 2008 | 23.1°C | 15.9°C | 8.6°C | 29.5°C | 2.8°C | 6 mm | 51% | 1.5 m/s | 5 |
| 2007 | 22.1°C | 15.1°C | 8.1°C | 31.4°C | 1.1°C | 14 mm | 56% | 1.7 m/s | 4.9 |
| 2006 | 24.0°C | 16.7°C | 9.4°C | 33.9°C | 3.6°C | 11 mm | 50% | 1.5 m/s | 4.8 |
| 2005 | 22.0°C | 14.9°C | 7.8°C | 30.6°C | 3.7°C | 26 mm | 54% | 1.4 m/s | 4.8 |
| 2004 | 21.3°C | 14.7°C | 8.2°C | 28.0°C | 3.7°C | 24 mm | 63% | 1.5 m/s | 4.4 |
| 2003 | 24.7°C | 17.5°C | 10.3°C | 34.8°C | 4.2°C | 8 mm | 50% | 1.6 m/s | 4.8 |
| 2002 | 23.4°C | 16.0°C | 8.5°C | 32.4°C | 2.6°C | 4 mm | 50% | 1.5 m/s | 4.9 |
| 2001 | 24.8°C | 17.3°C | 9.8°C | 31.2°C | 2.9°C | 5 mm | 50% | 1.5 m/s | 4.9 |
| 2000 | 20.8°C | 14.3°C | 7.7°C | 30.1°C | -0.1°C | 30 mm | 60% | 1.7 m/s | 4.5 |
| 1999 | 22.2°C | 14.9°C | 7.6°C | 29.3°C | 0.7°C | 2 mm | 51% | 1.5 m/s | 5.3 |
| 1998 | 25.6°C | 18.3°C | 11.0°C | 34.0°C | 7.1°C | 10 mm | 53% | 1.5 m/s | 5.1 |
| 1997 | 21.3°C | 15.2°C | 9.0°C | 27.7°C | 4.9°C | 47 mm | 66% | 1.6 m/s | 4.5 |
| 1996 | 20.2°C | 13.4°C | 6.7°C | 27.6°C | 1.2°C | 24 mm | 64% | 1.5 m/s | 4.4 |
| 1995 | 22.9°C | 16.3°C | 9.8°C | 30.0°C | 4.0°C | 42 mm | 60% | 1.4 m/s | 4.5 |
| 1994 | 24.6°C | 17.4°C | 10.3°C | 29.9°C | 5.5°C | 20 mm | 53% | 1.4 m/s | 4.6 |
| 1993 | 23.3°C | 16.0°C | 8.7°C | 31.5°C | 1.6°C | 2 mm | 53% | 1.4 m/s | 5.1 |
| 1992 | 20.4°C | 13.7°C | 7.0°C | 28.4°C | 1.7°C | 39 mm | 60% | 1.6 m/s | 4.5 |
| 1991 | 24.1°C | 16.8°C | 9.4°C | 29.8°C | 5.0°C | 5 mm | 53% | 1.4 m/s | 5.2 |
| 1990 | 26.2°C | 18.3°C | 10.5°C | 30.7°C | 5.8°C | 3 mm | 52% | 1.4 m/s | 5 |
| 1989 | 22.9°C | 15.6°C | 8.3°C | 29.2°C | 4.5°C | 5 mm | 52% | 1.5 m/s | 5 |
| 1988 | 22.3°C | 15.1°C | 7.9°C | 34.7°C | 3.0°C | 25 mm | 55% | 1.6 m/s | 4.5 |
| 1987 | 25.0°C | 17.4°C | 9.8°C | 33.8°C | 3.2°C | 4 mm | 49% | 1.4 m/s | 4.9 |
| 1986 | 18.0°C | 12.2°C | 6.4°C | 30.3°C | 2.2°C | 64 mm | 67% | 1.5 m/s | 4 |
| 1985 ❄️ | 17.8°C | 11.7°C | 5.7°C | 25.9°C | -0.7°C | 51 mm | 63% | 1.5 m/s | 4.2 |
| 1984 | 19.2°C | 12.6°C | 6.1°C | 28.5°C | 0.4°C | 35 mm | 62% | 1.6 m/s | 4.2 |
| 1983 | 18.9°C | 12.3°C | 5.7°C | 24.9°C | -0.7°C | 31 mm | 63% | 1.5 m/s | — |
| 1982 | 20.0°C | 13.9°C | 7.8°C | 28.1°C | 2.6°C | 59 mm | 64% | 1.6 m/s | — |
| 1981 | 22.2°C | 15.3°C | 8.4°C | 31.8°C | 2.1°C | 35 mm | 56% | 1.5 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 22.7°C with lows near 8.9°C (mean 15.8°C), based on 45 years of NASA POWER data.
September averages 21 mm of rainfall in Yakima, one of the drier months. The wettest on record was 71 mm in 2013.
The hottest September reached 35.4°C in 2017. The coldest dipped to -0.9°C in 2019.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 4°C. Daytime highs moved from 19.6°C to 24.3°C and overnight lows from 6.7°C to 10.2°C over the same span.
September is one of the warmer months of the year in Yakima and one of the drier months, so plan for around 22.7°C daytime highs and 8.9°C at night.
Not quite — September is the 9th coolest month in Yakima, averaging 15.8°C.
For September in Yakima, pack light layers you can adjust through the day, with typical highs of 22.7°C and lows of 8.9°C.
Relative humidity in September averages 56% — moderately humid.
Average wind speed in September is 1.5 m/s. The windiest September on record averaged 1.7 m/s (2000).
The wettest September on record was 2013 with 71 mm. On average, September sees 21 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 Yakima 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.
