September is one of the warmer months of the year in Riverdale, with average highs near 29.7°C and lows around 17.1°C (mean 23.4°C). It is one of the drier months, averaging 92 mm of rainfall and 70% relative humidity across the period.
September is one of the warmer months of the year in Riverdale. Across 45 years of records, the warmest September in Riverdale was 2019 — when the month averaged 28.1°C — while the coldest was 1994 at 20.6°C. Typical September days reach 29.7°C with nights near 17.1°C. The long-term trend is warming, about 0.5°C per decade.
September is one of the drier months in Riverdale, averaging 92 mm of rainfall. The wettest September on record was 2004 with 282 mm, while the driest was 1984 at 8 mm.
Relative humidity in Riverdale during September averages 70%. The most humid September was 1992 at 83%, and the least humid was 2019 at 52%.
September receives about 4.7 kWh/m²/day of solar energy in Riverdale. The sunniest September was 2019 at 5.8 kWh/m²/day, and the cloudiest were 1988 and 2002 at 3.8.
Average wind speed in Riverdale during September is 1.1 m/s. The windiest September was 2004 at 1.8 m/s, while the calmest was 2023 at 0.9 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 22.6°C | 23.2°C | 23.0°C | 24.6°C | 23.7°C | +1.1°C |
| Avg High | 28.9°C | 29.6°C | 29.0°C | 31.0°C | 29.9°C | +1°C |
| Avg Low | 16.4°C | 16.8°C | 17.0°C | 18.1°C | 17.5°C | +1.1°C |
| Avg Rain | 88 mm | 95 mm | 106 mm | 73 mm | 99 mm | +11 mm |
September temperatures in Riverdale have risen by about 1.6°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 5.3°C (1983) to a record high of 39.3°C (2019).
Rainfall in September is one of the drier months, averaging 92 mm, with a wettest year of 282 mm.
One of the best times to visit Riverdale
September is one of the best times to visit Riverdale. Expect days averaging 29.7°C and nights around 17.1°C (mean 23.4°C) — warmer than Riverdale's yearly average — with higher rainfall (92 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 | 31.8°C | 24.9°C | 18.0°C | 35.3°C | 13.6°C | 32 mm | 63% | 1 m/s | 5.2 |
| 2024 | 30.8°C | 24.9°C | 19.0°C | 37.5°C | 15.8°C | 227 mm | 69% | 1.4 m/s | 4.2 |
| 2023 | 30.8°C | 24.1°C | 17.5°C | 35.1°C | 12.7°C | 43 mm | 65% | 0.9 m/s | 5 |
| 2022 | 29.6°C | 23.0°C | 16.4°C | 35.8°C | 8.1°C | 55 mm | 68% | 1.2 m/s | 5.2 |
| 2021 | 28.6°C | 22.7°C | 16.9°C | 32.4°C | 8.5°C | 78 mm | 74% | 1 m/s | 4.8 |
| 2020 | 27.8°C | 22.5°C | 17.2°C | 34.3°C | 8.1°C | 158 mm | 77% | 1.3 m/s | 4.5 |
| 2019 🔥 | 35.8°C | 28.1°C | 20.5°C | 39.3°C | 15.1°C | 19 mm | 52% | 1.1 m/s | 5.8 |
| 2018 | 32.8°C | 26.7°C | 20.7°C | 36.2°C | 18.7°C | 63 mm | 71% | 1 m/s | 4.8 |
| 2017 | 28.9°C | 22.5°C | 16.1°C | 33.4°C | 11.0°C | 116 mm | 70% | 1.2 m/s | 5.3 |
| 2016 | 32.8°C | 26.0°C | 19.2°C | 36.3°C | 10.3°C | 55 mm | 64% | 1 m/s | 5.4 |
| 2015 | 28.6°C | 23.0°C | 17.4°C | 35.1°C | 10.1°C | 107 mm | 75% | 1 m/s | 4.4 |
| 2014 | 30.6°C | 24.6°C | 18.7°C | 34.7°C | 12.2°C | 70 mm | 73% | 1 m/s | 4.4 |
| 2013 | 28.5°C | 22.6°C | 16.8°C | 31.6°C | 10.9°C | 57 mm | 78% | 1 m/s | 4.9 |
| 2012 | 30.0°C | 23.4°C | 16.8°C | 35.2°C | 8.4°C | 70 mm | 70% | 1 m/s | 4.6 |
| 2011 | 29.6°C | 23.3°C | 17.1°C | 37.5°C | 12.4°C | 95 mm | 68% | 1.3 m/s | 4.5 |
| 2010 | 32.7°C | 25.4°C | 18.0°C | 36.4°C | 12.1°C | 81 mm | 61% | 1 m/s | 5.6 |
| 2009 | 27.6°C | 22.8°C | 18.0°C | 31.8°C | 8.1°C | 214 mm | 81% | 1.1 m/s | 3.9 |
| 2008 | 30.3°C | 23.8°C | 17.3°C | 34.4°C | 9.9°C | 24 mm | 69% | 1.3 m/s | 4.9 |
| 2007 | 31.1°C | 24.5°C | 17.8°C | 35.2°C | 10.0°C | 64 mm | 66% | 1.2 m/s | 5 |
| 2006 | 29.1°C | 22.6°C | 16.1°C | 34.0°C | 8.6°C | 77 mm | 70% | 1.1 m/s | 4.8 |
| 2005 | 30.8°C | 24.1°C | 17.5°C | 34.2°C | 14.1°C | 11 mm | 69% | 1.2 m/s | 5.5 |
| 2004 🌧️ | 26.7°C | 21.7°C | 16.7°C | 32.0°C | 9.8°C | 282 mm | 81% | 1.8 m/s | 4.4 |
| 2003 | 27.4°C | 21.5°C | 15.6°C | 31.1°C | 6.2°C | 65 mm | 76% | 1.1 m/s | 5 |
| 2002 | 30.6°C | 25.0°C | 19.5°C | 37.1°C | 15.5°C | 149 mm | 72% | 1.4 m/s | 3.8 |
| 2001 | 28.9°C | 22.0°C | 15.1°C | 33.5°C | 5.8°C | 65 mm | 65% | 1.1 m/s | 5 |
| 2000 | 27.3°C | 21.6°C | 15.9°C | 32.0°C | 7.1°C | 111 mm | 77% | 1.3 m/s | 4.2 |
| 1999 | 31.1°C | 23.3°C | 15.4°C | 37.6°C | 6.9°C | 61 mm | 54% | 1.2 m/s | 5 |
| 1998 | 31.2°C | 24.7°C | 18.1°C | 35.2°C | 11.4°C | 85 mm | 68% | 1.1 m/s | 4.7 |
| 1997 | 31.2°C | 24.3°C | 17.5°C | 36.4°C | 10.9°C | 152 mm | 63% | 1.1 m/s | 4.8 |
| 1996 | 28.9°C | 22.6°C | 16.2°C | 33.5°C | 11.1°C | 117 mm | 71% | 1.2 m/s | 4.4 |
| 1995 | 28.8°C | 22.7°C | 16.6°C | 33.9°C | 10.3°C | 82 mm | 74% | 1.2 m/s | 4.6 |
| 1994 ❄️ | 26.0°C | 20.6°C | 15.2°C | 30.4°C | 9.3°C | 127 mm | 82% | 1.1 m/s | 4.8 |
| 1993 | 31.6°C | 24.4°C | 17.3°C | 35.0°C | 6.4°C | 65 mm | 64% | 1.1 m/s | 4.9 |
| 1992 | 27.0°C | 22.1°C | 17.2°C | 30.4°C | 8.6°C | 131 mm | 83% | 1 m/s | 4 |
| 1991 | 28.8°C | 22.7°C | 16.5°C | 35.5°C | 6.9°C | 62 mm | 74% | 1 m/s | 4.9 |
| 1990 | 31.7°C | 24.6°C | 17.5°C | 37.5°C | 6.6°C | 66 mm | 62% | 1 m/s | 5.1 |
| 1989 | 27.5°C | 22.2°C | 17.0°C | 32.8°C | 9.8°C | 192 mm | 78% | 1.3 m/s | 3.9 |
| 1988 | 27.7°C | 22.4°C | 17.2°C | 31.9°C | 12.1°C | 160 mm | 80% | 1.2 m/s | 3.8 |
| 1987 | 29.9°C | 23.6°C | 17.3°C | 33.4°C | 11.0°C | 71 mm | 67% | 1.1 m/s | 4.5 |
| 1986 | 29.6°C | 23.9°C | 18.3°C | 34.2°C | 13.7°C | 79 mm | 76% | 1 m/s | 4.1 |
| 1985 | 29.4°C | 22.5°C | 15.6°C | 33.8°C | 7.2°C | 50 mm | 67% | 1.2 m/s | 5 |
| 1984 | 28.9°C | 21.8°C | 14.8°C | 34.9°C | 10.0°C | 8 mm | 66% | 1.2 m/s | 5.1 |
| 1983 | 27.5°C | 21.7°C | 15.9°C | 34.8°C | 5.3°C | 124 mm | 73% | 1.2 m/s | — |
| 1982 | 28.8°C | 22.3°C | 15.8°C | 33.5°C | 7.1°C | 55 mm | 68% | 1.1 m/s | — |
| 1981 | 30.4°C | 23.0°C | 15.6°C | 33.4°C | 7.4°C | 49 mm | 60% | 1 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 29.7°C with lows near 17.1°C (mean 23.4°C), based on 45 years of NASA POWER data.
September averages 92 mm of rainfall in Riverdale, one of the drier months. The wettest on record was 282 mm in 2004.
The hottest September reached 39.3°C in 2019. The coldest dipped to 5.3°C in 1983.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.6°C. Daytime highs moved from 29°C to 30.3°C and overnight lows from 15.5°C to 17.6°C over the same span.
September is one of the warmer months of the year in Riverdale and one of the drier months, so plan for around 29.7°C daytime highs and 17.1°C at night.
Not quite — September is the 9th coolest month in Riverdale, averaging 23.4°C.
For September in Riverdale, pack light layers you can adjust through the day, with typical highs of 29.7°C and lows of 17.1°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 70% — moderately humid.
Average wind speed in September is 1.1 m/s. The windiest September on record averaged 1.8 m/s (2004).
The wettest September on record was 2004 with 282 mm. On average, September sees 92 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 Riverdale 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.
