September is one of the warmer months of the year in Nelson, with average highs near 16.6°C and lows around 4.6°C (mean 10.6°C). It is one of the drier months, averaging 44 mm of rainfall and 66% relative humidity across the period.
September is one of the warmer months of the year in Nelson. Across 45 years of records, the warmest September in Nelson was 2025 — when the month averaged 14.5°C — while the coldest was 1985 at 6.5°C. Typical September days reach 16.6°C with nights near 4.6°C. The long-term trend is warming, about 0.4°C per decade.
September is one of the drier months in Nelson, averaging 44 mm of rainfall. The wettest September on record was 2013 with 114 mm, while the driest was 1990 at 3 mm.
Relative humidity in Nelson during September averages 66%. The most humid Septembers were 2013 and 2019 at 79%, and the least humid was 1987 at 50%.
September receives about 3.9 kWh/m²/day of solar energy in Nelson. The sunniest Septembers were 1990 and 1993 at 4.8 kWh/m²/day, and the cloudiest was 2019 at 3.
Average wind speed in Nelson during September is 0.4 m/s. The windiest Septembers were 1990 and 2012 at 0.5 m/s, while the calmest were 2016, 2019 and 2021, among others at 0.3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 9.2°C | 11.4°C | 10.7°C | 10.0°C | 12.1°C | +2.9°C |
| Avg High | 15.1°C | 17.8°C | 17.1°C | 15.5°C | 17.7°C | +2.6°C |
| Avg Low | 3.4°C | 5.1°C | 4.4°C | 4.5°C | 6.5°C | +3.1°C |
| Avg Rain | 52 mm | 28 mm | 37 mm | 60 mm | 42 mm | -10 mm |
September temperatures in Nelson have risen by about 4.2°C between 1981–1985 and 2021–2025.
September has ranged from a record low of -7.1°C (2000) to a record high of 32.5°C (1988).
Rainfall in September is one of the drier months, averaging 44 mm, with a wettest year of 114 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.2°C per decade while lows rose 0.5°C per decade, narrowing the gap between day and night.
One of the best times to visit Nelson
September is one of the best times to visit Nelson. Expect days averaging 16.6°C and nights around 4.6°C (mean 10.6°C) — warmer than Nelson's yearly average — with moderate rainfall (44 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 🔥 | 20.1°C | 14.5°C | 8.9°C | 28.4°C | 3.4°C | 30 mm | 71% | 0.4 m/s | 4 |
| 2024 | 18.3°C | 12.5°C | 6.6°C | 29.2°C | -2.0°C | 33 mm | 70% | 0.4 m/s | 4.2 |
| 2023 | 15.7°C | 10.6°C | 5.6°C | 21.1°C | -1.6°C | 51 mm | 73% | 0.4 m/s | 3.7 |
| 2022 | 18.9°C | 12.8°C | 6.7°C | 26.7°C | 0.7°C | 30 mm | 66% | 0.4 m/s | 4 |
| 2021 | 15.8°C | 10.4°C | 5.0°C | 24.1°C | -2.4°C | 69 mm | 71% | 0.3 m/s | 3.6 |
| 2020 | 17.4°C | 11.8°C | 6.1°C | 24.4°C | -0.3°C | 39 mm | 73% | 0.4 m/s | 3.8 |
| 2019 | 13.7°C | 9.2°C | 4.6°C | 23.9°C | -5.7°C | 104 mm | 79% | 0.3 m/s | 3 |
| 2018 | 13.0°C | 8.0°C | 2.9°C | 21.6°C | -2.2°C | 82 mm | 76% | 0.4 m/s | 3.6 |
| 2017 | 16.6°C | 11.1°C | 5.5°C | 27.9°C | -0.1°C | 23 mm | 69% | 0.4 m/s | 3.7 |
| 2016 | 14.1°C | 8.9°C | 3.8°C | 20.5°C | -0.7°C | 64 mm | 77% | 0.3 m/s | 3.5 |
| 2015 | 14.0°C | 8.6°C | 3.2°C | 24.4°C | -2.3°C | 52 mm | 72% | 0.4 m/s | 3.5 |
| 2014 | 16.5°C | 10.7°C | 4.8°C | 23.3°C | -3.8°C | 47 mm | 72% | 0.4 m/s | 4.1 |
| 2013 🌧️ | 15.7°C | 10.9°C | 6.2°C | 24.3°C | -0.9°C | 114 mm | 79% | 0.3 m/s | 3.2 |
| 2012 | 18.7°C | 11.9°C | 5.1°C | 23.3°C | -0.9°C | 29 mm | 64% | 0.5 m/s | 4.6 |
| 2011 | 19.1°C | 12.3°C | 5.5°C | 26.6°C | -0.3°C | 19 mm | 60% | 0.4 m/s | 4.5 |
| 2010 | 13.9°C | 8.7°C | 3.4°C | 21.8°C | -2.4°C | 66 mm | 77% | 0.3 m/s | 3.2 |
| 2009 | 19.8°C | 12.9°C | 5.9°C | 27.3°C | -1.1°C | 23 mm | 55% | 0.4 m/s | 4.4 |
| 2008 | 17.8°C | 11.1°C | 4.4°C | 26.7°C | -1.0°C | 21 mm | 58% | 0.4 m/s | 4.2 |
| 2007 | 15.7°C | 9.5°C | 3.3°C | 25.0°C | -2.4°C | 34 mm | 65% | 0.4 m/s | 4 |
| 2006 | 18.7°C | 12.0°C | 5.3°C | 28.9°C | -2.5°C | 21 mm | 60% | 0.4 m/s | 4.2 |
| 2005 | 14.8°C | 8.9°C | 3.0°C | 23.2°C | -3.2°C | 57 mm | 67% | 0.4 m/s | 3.9 |
| 2004 | 14.5°C | 9.1°C | 3.8°C | 20.8°C | -2.9°C | 68 mm | 74% | 0.3 m/s | 3.3 |
| 2003 | 18.2°C | 11.6°C | 5.0°C | 29.4°C | -0.4°C | 37 mm | 60% | 0.4 m/s | 4 |
| 2002 | 16.6°C | 10.5°C | 4.4°C | 25.6°C | -1.8°C | 33 mm | 60% | 0.4 m/s | 3.9 |
| 2001 | 19.6°C | 12.5°C | 5.3°C | 27.8°C | 1.5°C | 21 mm | 53% | 0.4 m/s | 4.2 |
| 2000 | 15.0°C | 9.1°C | 3.3°C | 22.8°C | -7.1°C | 55 mm | 68% | 0.3 m/s | 3.5 |
| 1999 | 15.7°C | 9.3°C | 3.0°C | 22.6°C | -4.1°C | 14 mm | 62% | 0.4 m/s | 4.3 |
| 1998 | 20.6°C | 14.3°C | 8.0°C | 27.2°C | 2.6°C | 19 mm | 57% | 0.4 m/s | 4.5 |
| 1997 | 16.4°C | 10.7°C | 5.1°C | 22.7°C | -1.2°C | 93 mm | 73% | 0.3 m/s | 3.7 |
| 1996 | 14.4°C | 8.8°C | 3.2°C | 25.5°C | -3.0°C | 36 mm | 69% | 0.4 m/s | 3.2 |
| 1995 | 19.6°C | 12.8°C | 6.0°C | 27.7°C | 0.2°C | 29 mm | 55% | 0.4 m/s | 4.4 |
| 1994 | 20.2°C | 13.7°C | 7.2°C | 26.7°C | 1.2°C | 19 mm | 52% | 0.4 m/s | 4.1 |
| 1993 | 17.2°C | 10.6°C | 4.0°C | 24.3°C | -2.2°C | 21 mm | 61% | 0.4 m/s | 4.8 |
| 1992 | 14.5°C | 8.6°C | 2.7°C | 23.6°C | -4.1°C | 35 mm | 63% | 0.3 m/s | 3.8 |
| 1991 | 17.9°C | 11.3°C | 4.6°C | 23.6°C | -0.7°C | 17 mm | 62% | 0.4 m/s | 4.6 |
| 1990 | 21.1°C | 14.0°C | 6.9°C | 25.5°C | 1.3°C | 3 mm | 54% | 0.5 m/s | 4.8 |
| 1989 | 18.0°C | 11.4°C | 4.8°C | 23.5°C | -0.4°C | 14 mm | 58% | 0.4 m/s | 4.4 |
| 1988 | 17.5°C | 10.9°C | 4.3°C | 32.5°C | -1.6°C | 71 mm | 61% | 0.4 m/s | 3.6 |
| 1987 | 20.7°C | 13.7°C | 6.7°C | 28.2°C | 0.4°C | 20 mm | 50% | 0.4 m/s | 4.6 |
| 1986 | 12.2°C | 7.1°C | 2.0°C | 22.6°C | -2.8°C | 74 mm | 75% | 0.3 m/s | 3.3 |
| 1985 ❄️ | 12.0°C | 6.5°C | 1.1°C | 18.5°C | -3.9°C | 92 mm | 71% | 0.3 m/s | 3.6 |
| 1984 | 12.9°C | 7.2°C | 1.6°C | 21.8°C | -4.3°C | 47 mm | 68% | 0.4 m/s | 3.5 |
| 1983 | 12.7°C | 7.2°C | 1.7°C | 17.4°C | -4.7°C | 23 mm | 71% | 0.4 m/s | — |
| 1982 | 14.7°C | 9.2°C | 3.8°C | 25.9°C | -3.1°C | 71 mm | 77% | 0.4 m/s | — |
| 1981 | 15.4°C | 9.9°C | 4.4°C | 27.2°C | -2.3°C | 57 mm | 70% | 0.4 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 16.6°C with lows near 4.6°C (mean 10.6°C), based on 45 years of NASA POWER data.
September averages 44 mm of rainfall in Nelson, one of the drier months. The wettest on record was 114 mm in 2013.
The hottest September reached 32.5°C in 1988. The coldest dipped to -7.1°C in 2000.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 4.2°C. Daytime highs moved from 13.5°C to 17.8°C and overnight lows from 2.5°C to 6.6°C over the same span.
September is one of the warmer months of the year in Nelson and one of the drier months, so plan for around 16.6°C daytime highs and 4.6°C at night.
Not quite — September is the 9th coolest month in Nelson, averaging 10.6°C.
For September in Nelson, pack warm layers and a jacket for chilly mornings, with typical highs of 16.6°C and lows of 4.6°C.
Relative humidity in September averages 66% — moderately humid.
Average wind speed in September is 0.4 m/s. The windiest September on record averaged 0.5 m/s (1990).
The wettest September on record was 2013 with 114 mm. On average, September sees 44 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 Nelson 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.
