September is one of the warmer months of the year in Greenock, with average highs near 14.3°C and lows around 9.2°C (mean 11.8°C). It is about average for rainfall, averaging 124 mm of rainfall and 88% relative humidity across the period.
September is one of the warmer months of the year in Greenock. Across 45 years of records, the warmest Septembers in Greenock were 2006 and 2021 — when the month averaged 13.6°C — while the coldest was 1986 at 9.8°C. Typical September days reach 14.3°C with nights near 9.2°C. The long-term trend is warming, about 0.3°C per decade.
September is about average for rainfall in Greenock, averaging 124 mm of rainfall. The wettest September on record was 1981 with 217 mm, while the driest was 2014 at 29 mm.
Relative humidity in Greenock during September averages 88%. The most humid September was 1985 at 91%, and the least humid was 1991 at 86%.
September receives about 2.6 kWh/m²/day of solar energy in Greenock. The sunniest September was 1991 at 3.1 kWh/m²/day, and the cloudiest was 2000 at 2.1.
Average wind speed in Greenock during September is 4 m/s. The windiest Septembers were 1983 and 2004 at 5 m/s, while the calmest was 2014 at 2.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 11.0°C | 11.6°C | 12.1°C | 11.7°C | 12.5°C | +1.5°C |
| Avg High | 13.4°C | 14.3°C | 14.6°C | 14.2°C | 15.3°C | +1.9°C |
| Avg Low | 8.6°C | 8.9°C | 9.6°C | 9.3°C | 9.7°C | +1.1°C |
| Avg Rain | 154 mm | 106 mm | 127 mm | 121 mm | 109 mm | -44 mm |
September temperatures in Greenock have risen by about 1.4°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 1.9°C (2007) to a record high of 23.9°C (2023).
Rainfall in September is about average for rainfall, averaging 124 mm, with a wettest year of 217 mm.
One of the best times to visit Greenock
September is one of the best times to visit Greenock. Expect days averaging 14.3°C and nights around 9.2°C (mean 11.8°C) — warmer than Greenock's yearly average — with higher rainfall (124 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 | 14.5°C | 12.0°C | 9.5°C | 17.0°C | 5.5°C | 113 mm | 87% | 4.2 m/s | 2.6 |
| 2024 | 14.6°C | 11.5°C | 8.4°C | 20.7°C | 4.9°C | 55 mm | 88% | 3.6 m/s | 2.8 |
| 2023 | 16.3°C | 13.5°C | 10.6°C | 23.9°C | 6.6°C | 147 mm | 88% | 4 m/s | 2.8 |
| 2022 | 15.5°C | 12.6°C | 9.7°C | 19.6°C | 5.3°C | 127 mm | 88% | 3.7 m/s | 2.9 |
| 2021 | 16.3°C | 13.6°C | 10.8°C | 22.3°C | 7.5°C | 96 mm | 89% | 3.2 m/s | 2.4 |
| 2020 | 14.3°C | 11.7°C | 9.1°C | 18.8°C | 2.6°C | 118 mm | 88% | 4.1 m/s | 2.7 |
| 2019 | 14.4°C | 11.9°C | 9.4°C | 18.0°C | 6.6°C | 127 mm | 89% | 3.9 m/s | 2.7 |
| 2018 | 13.2°C | 10.9°C | 8.6°C | 17.5°C | 5.4°C | 144 mm | 87% | 4.8 m/s | 2.6 |
| 2017 | 13.9°C | 11.7°C | 9.4°C | 16.3°C | 5.7°C | 147 mm | 90% | 3.8 m/s | 2.4 |
| 2016 | 15.0°C | 12.9°C | 10.7°C | 18.8°C | 7.4°C | 159 mm | 90% | 4.5 m/s | 2.5 |
| 2015 | 14.2°C | 11.2°C | 8.3°C | 16.9°C | 6.4°C | 47 mm | 88% | 3.2 m/s | 3 |
| 2014 | 15.6°C | 12.8°C | 10.0°C | 18.6°C | 6.8°C | 29 mm | 89% | 2.7 m/s | 2.9 |
| 2013 | 13.9°C | 11.4°C | 8.9°C | 16.8°C | 5.8°C | 97 mm | 89% | 4 m/s | 2.5 |
| 2012 | 12.7°C | 10.5°C | 8.3°C | 16.2°C | 3.3°C | 133 mm | 88% | 4.9 m/s | 2.5 |
| 2011 | 14.1°C | 12.1°C | 10.0°C | 18.5°C | 7.1°C | 197 mm | 90% | 4.9 m/s | 2.5 |
| 2010 | 14.6°C | 12.0°C | 9.4°C | 18.4°C | 3.5°C | 125 mm | 88% | 4.2 m/s | 2.8 |
| 2009 | 14.1°C | 12.0°C | 10.0°C | 17.3°C | 7.4°C | 99 mm | 90% | 4.2 m/s | 2.6 |
| 2008 | 14.0°C | 11.6°C | 9.2°C | 16.0°C | 6.5°C | 126 mm | 89% | 3.5 m/s | 2.3 |
| 2007 | 13.9°C | 11.2°C | 8.5°C | 17.5°C | 1.9°C | 84 mm | 89% | 4 m/s | 2.6 |
| 2006 🔥 | 16.1°C | 13.6°C | 11.0°C | 19.3°C | 7.4°C | 210 mm | 90% | 3.8 m/s | 2.5 |
| 2005 | 14.7°C | 12.4°C | 10.2°C | 21.2°C | 4.5°C | 131 mm | 89% | 4.7 m/s | 2.4 |
| 2004 | 14.5°C | 12.2°C | 10.0°C | 18.6°C | 6.3°C | 176 mm | 89% | 5 m/s | 2.7 |
| 2003 | 14.6°C | 12.1°C | 9.5°C | 17.8°C | 5.0°C | 101 mm | 88% | 3.2 m/s | 2.7 |
| 2002 | 15.2°C | 12.4°C | 9.6°C | 18.6°C | 5.6°C | 54 mm | 89% | 2.8 m/s | 2.7 |
| 2001 | 14.2°C | 11.4°C | 8.6°C | 16.8°C | 5.1°C | 93 mm | 89% | 4.1 m/s | 2.6 |
| 2000 | 14.8°C | 12.3°C | 9.8°C | 18.1°C | 6.7°C | 199 mm | 89% | 3.8 m/s | 2.1 |
| 1999 | 15.2°C | 12.7°C | 10.3°C | 19.5°C | 7.7°C | 167 mm | 90% | 4.1 m/s | 2.4 |
| 1998 | 15.1°C | 12.5°C | 10.0°C | 20.4°C | 4.6°C | 105 mm | 90% | 3.4 m/s | 2.8 |
| 1997 | 14.2°C | 11.5°C | 8.8°C | 17.2°C | 4.4°C | 88 mm | 88% | 4.1 m/s | 2.8 |
| 1996 | 15.2°C | 12.2°C | 9.2°C | 19.9°C | 4.6°C | 70 mm | 87% | 3.7 m/s | 3 |
| 1995 | 14.6°C | 11.8°C | 9.0°C | 17.0°C | 4.7°C | 113 mm | 87% | 3.5 m/s | 2.7 |
| 1994 | 13.3°C | 10.7°C | 8.0°C | 17.4°C | 5.4°C | 79 mm | 88% | 3.6 m/s | 2.5 |
| 1993 | 13.6°C | 10.7°C | 7.8°C | 18.0°C | 4.0°C | 63 mm | 87% | 3.7 m/s | 2.6 |
| 1992 | 13.0°C | 10.8°C | 8.5°C | 17.4°C | 6.0°C | 168 mm | 89% | 4.3 m/s | 2.5 |
| 1991 | 15.1°C | 12.0°C | 8.9°C | 22.4°C | 3.4°C | 102 mm | 86% | 4 m/s | 3.1 |
| 1990 | 13.3°C | 10.7°C | 8.2°C | 18.2°C | 3.1°C | 104 mm | 87% | 4.3 m/s | 2.6 |
| 1989 | 13.9°C | 11.2°C | 8.5°C | 16.2°C | 5.5°C | 114 mm | 88% | 3.9 m/s | 2.4 |
| 1988 | 13.0°C | 11.0°C | 8.9°C | 17.8°C | 3.9°C | 155 mm | 89% | 4.7 m/s | 2.4 |
| 1987 | 13.1°C | 10.9°C | 8.8°C | 16.4°C | 4.8°C | 151 mm | 87% | 4.6 m/s | 2.8 |
| 1986 ❄️ | 12.6°C | 9.8°C | 7.0°C | 16.0°C | 2.4°C | 54 mm | 86% | 3.7 m/s | 2.9 |
| 1985 | 13.4°C | 11.2°C | 9.1°C | 17.5°C | 5.1°C | 209 mm | 91% | 4 m/s | 2.3 |
| 1984 | 13.4°C | 10.9°C | 8.4°C | 17.0°C | 5.4°C | 150 mm | 87% | 3.6 m/s | 2.4 |
| 1983 | 13.2°C | 10.9°C | 8.6°C | 16.3°C | 4.6°C | 155 mm | 87% | 5 m/s | — |
| 1982 | 13.3°C | 10.8°C | 8.4°C | 17.8°C | 5.2°C | 176 mm | 87% | 4.8 m/s | — |
| 1981 🌧️ | 14.3°C | 12.0°C | 9.7°C | 18.5°C | 7.7°C | 217 mm | 88% | 4.4 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 14.3°C with lows near 9.2°C (mean 11.8°C), based on 45 years of NASA POWER data.
September averages 124 mm of rainfall in Greenock, about average for rainfall. The wettest on record was 217 mm in 1981.
The hottest September reached 23.9°C in 2023. The coldest dipped to 1.9°C in 2007.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.4°C. Daytime highs moved from 13.5°C to 15.4°C and overnight lows from 8.8°C to 9.8°C over the same span.
September is one of the warmer months of the year in Greenock and about average for rainfall, so plan for around 14.3°C daytime highs and 9.2°C at night.
Not quite — September is the 9th coolest month in Greenock, averaging 11.8°C.
For September in Greenock, pack light layers you can adjust through the day, with typical highs of 14.3°C and lows of 9.2°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 88% — quite humid.
Average wind speed in September is 4 m/s. The windiest September on record averaged 5 m/s (1983).
The wettest September on record was 1981 with 217 mm. On average, September sees 124 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 Greenock 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.
