December is one of the warmer months of the year in Whanganui, with average highs near 19.4°C and lows around 13.3°C (mean 16.4°C). It is about average for rainfall, averaging 87 mm of rainfall and 79% relative humidity across the period.
December is one of the warmer months of the year in Whanganui. Across 45 years of records, the warmest December in Whanganui was 1984 — when the month averaged 18.3°C — while the coldest was 2006 at 13.4°C. Typical December days reach 19.4°C with nights near 13.3°C. The long-term December temperature trend is broadly flat.
December is about average for rainfall in Whanganui, averaging 87 mm of rainfall. The wettest December on record was 2021 with 232 mm, while the driest was 2017 at 28 mm.
Relative humidity in Whanganui during December averages 79%. The most humid December was 2021 at 85%, and the least humid was 1983 at 74%.
December receives about 6.2 kWh/m²/day of solar energy in Whanganui. The sunniest Decembers were 2015 and 2017 at 6.8 kWh/m²/day, and the cloudiest was 2001 at 4.8.
Average wind speed in Whanganui during December is 4.7 m/s. The windiest December was 1989 at 5.9 m/s, while the calmest was 2011 at 3.3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 16.7°C | 15.5°C | 16.1°C | 16.7°C | 17.0°C | +0.3°C |
| Avg High | 19.9°C | 18.5°C | 19.1°C | 19.8°C | 19.8°C | -0.1°C |
| Avg Low | 13.5°C | 12.5°C | 13.2°C | 13.6°C | 14.1°C | +0.6°C |
| Avg Rain | 83 mm | 77 mm | 82 mm | 83 mm | 125 mm | +42 mm |
December temperatures in Whanganui have risen by about 0.3°C between 1981–1985 and 2021–2025.
December has ranged from a record low of 7°C (1982) to a record high of 27.4°C (2012).
Rainfall in December is about average for rainfall, averaging 87 mm, with a wettest year of 232 mm.
One of the best times to visit Whanganui
December is one of the best times to visit Whanganui. Expect days averaging 19.4°C and nights around 13.3°C (mean 16.4°C) — warmer than Whanganui's yearly average — with higher rainfall (87 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 | 20.0°C | 16.9°C | 13.8°C | 22.4°C | 10.8°C | 128 mm | 79% | 5.2 m/s | — |
| 2024 | 19.9°C | 17.0°C | 14.1°C | 22.2°C | 10.9°C | 67 mm | 83% | 4.8 m/s | 6.3 |
| 2023 | 20.2°C | 17.2°C | 14.1°C | 23.8°C | 9.7°C | 85 mm | 83% | 4.6 m/s | 5.7 |
| 2022 | 19.9°C | 16.9°C | 14.0°C | 23.1°C | 10.1°C | 141 mm | 83% | 3.6 m/s | 6.4 |
| 2021 🌧️ | 20.8°C | 18.2°C | 15.7°C | 23.4°C | 13.9°C | 232 mm | 85% | 4.5 m/s | 6.1 |
| 2020 | 18.3°C | 15.5°C | 12.6°C | 21.6°C | 8.0°C | 95 mm | 82% | 5 m/s | 6.6 |
| 2019 | 19.7°C | 16.6°C | 13.6°C | 22.6°C | 10.3°C | 107 mm | 78% | 5.2 m/s | 6.5 |
| 2018 | 20.1°C | 17.3°C | 14.5°C | 23.0°C | 9.7°C | 123 mm | 83% | 3.8 m/s | 6.3 |
| 2017 | 21.3°C | 18.1°C | 14.8°C | 24.8°C | 11.5°C | 28 mm | 78% | 4.3 m/s | 6.8 |
| 2016 | 18.5°C | 15.4°C | 12.3°C | 21.9°C | 9.6°C | 51 mm | 80% | 4.7 m/s | 6.7 |
| 2015 | 18.4°C | 15.6°C | 12.9°C | 23.2°C | 9.6°C | 36 mm | 79% | 4.7 m/s | 6.8 |
| 2014 | 19.5°C | 16.3°C | 13.0°C | 22.6°C | 7.5°C | 93 mm | 79% | 4.2 m/s | 6.1 |
| 2013 | 19.9°C | 16.8°C | 13.7°C | 22.2°C | 10.3°C | 67 mm | 77% | 4.6 m/s | 6.2 |
| 2012 | 20.7°C | 17.3°C | 14.0°C | 27.4°C | 9.4°C | 83 mm | 78% | 4.5 m/s | 6.2 |
| 2011 | 19.3°C | 16.3°C | 13.2°C | 21.6°C | 8.8°C | 167 mm | 80% | 3.3 m/s | 5.9 |
| 2010 | 20.3°C | 17.2°C | 14.1°C | 23.2°C | 8.9°C | 74 mm | 80% | 4.7 m/s | 6 |
| 2009 | 17.9°C | 15.0°C | 12.1°C | 20.8°C | 8.5°C | 90 mm | 81% | 4.9 m/s | 6.6 |
| 2008 | 19.7°C | 16.5°C | 13.2°C | 22.7°C | 9.8°C | 81 mm | 79% | 4.6 m/s | 6.3 |
| 2007 | 20.4°C | 17.0°C | 13.5°C | 23.9°C | 10.7°C | 61 mm | 76% | 3.9 m/s | 5.7 |
| 2006 ❄️ | 16.0°C | 13.4°C | 10.7°C | 19.0°C | 7.4°C | 70 mm | 81% | 4.7 m/s | 6.1 |
| 2005 | 20.7°C | 17.8°C | 14.9°C | 25.1°C | 11.1°C | 69 mm | 79% | 4.5 m/s | 5.6 |
| 2004 | 16.5°C | 14.0°C | 11.6°C | 21.9°C | 8.5°C | 152 mm | 79% | 5.6 m/s | 5.6 |
| 2003 | 19.4°C | 16.3°C | 13.2°C | 23.0°C | 9.2°C | 64 mm | 80% | 5 m/s | 6 |
| 2002 | 18.9°C | 16.0°C | 13.1°C | 22.7°C | 9.8°C | 92 mm | 78% | 5.3 m/s | 6 |
| 2001 | 20.3°C | 17.7°C | 15.0°C | 24.9°C | 12.2°C | 90 mm | 80% | 5.1 m/s | 4.8 |
| 2000 | 20.8°C | 17.5°C | 14.2°C | 23.8°C | 10.5°C | 55 mm | 77% | 4.8 m/s | 5.8 |
| 1999 | 18.8°C | 15.5°C | 12.2°C | 22.4°C | 8.7°C | 31 mm | 76% | 4.4 m/s | 6.3 |
| 1998 | 19.9°C | 16.8°C | 13.7°C | 23.7°C | 10.8°C | 40 mm | 76% | 4.8 m/s | 6.3 |
| 1997 | 19.0°C | 15.7°C | 12.5°C | 22.6°C | 9.1°C | 64 mm | 74% | 5.2 m/s | 6.4 |
| 1996 | 17.7°C | 15.0°C | 12.2°C | 22.3°C | 8.7°C | 109 mm | 82% | 4.7 m/s | 5.9 |
| 1995 | 19.7°C | 16.7°C | 13.7°C | 23.2°C | 10.4°C | 89 mm | 82% | 4.5 m/s | 6.4 |
| 1994 | 18.4°C | 15.3°C | 12.2°C | 21.8°C | 8.4°C | 43 mm | 82% | 4.4 m/s | 6.6 |
| 1993 | 17.6°C | 14.6°C | 11.6°C | 22.4°C | 8.6°C | 102 mm | 81% | 4.5 m/s | 5.9 |
| 1992 | 17.6°C | 14.8°C | 12.0°C | 21.8°C | 7.0°C | 158 mm | 83% | 4 m/s | 5.5 |
| 1991 | 17.4°C | 14.7°C | 11.9°C | 21.0°C | 8.1°C | 93 mm | 83% | 4.1 m/s | 6.1 |
| 1990 | 18.9°C | 16.1°C | 13.2°C | 23.2°C | 10.1°C | 44 mm | 78% | 5.6 m/s | 6.5 |
| 1989 | 18.8°C | 15.7°C | 12.7°C | 22.4°C | 9.8°C | 80 mm | 75% | 5.9 m/s | 6.3 |
| 1988 | 21.3°C | 17.8°C | 14.2°C | 26.4°C | 10.7°C | 34 mm | 76% | 4.1 m/s | 6.5 |
| 1987 | 19.4°C | 16.3°C | 13.2°C | 23.6°C | 10.5°C | 99 mm | 78% | 4.8 m/s | 5.9 |
| 1986 | 19.6°C | 16.3°C | 12.9°C | 23.0°C | 8.7°C | 34 mm | 74% | 4.5 m/s | 6.5 |
| 1985 | 20.6°C | 17.4°C | 14.1°C | 23.3°C | 9.5°C | 129 mm | 77% | 4.1 m/s | 6.5 |
| 1984 🔥 | 21.8°C | 18.3°C | 14.7°C | 24.9°C | 12.6°C | 96 mm | 76% | 4.3 m/s | 6.1 |
| 1983 | 19.1°C | 15.9°C | 12.7°C | 25.0°C | 9.9°C | 89 mm | 74% | 4.9 m/s | — |
| 1982 | 17.4°C | 14.7°C | 12.0°C | 21.1°C | 7.0°C | 111 mm | 79% | 5.8 m/s | — |
| 1981 | 21.0°C | 18.0°C | 14.9°C | 25.2°C | 12.3°C | 71 mm | 78% | 4.6 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 19.4°C with lows near 13.3°C (mean 16.4°C), based on 45 years of NASA POWER data.
December averages 87 mm of rainfall in Whanganui, about average for rainfall. The wettest on record was 232 mm in 2021.
The hottest December reached 27.4°C in 2012. The coldest dipped to 7°C in 1982.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 0.3°C. Daytime highs moved from 20°C to 20.2°C and overnight lows from 13.7°C to 14.3°C over the same span.
December is one of the warmer months of the year in Whanganui and about average for rainfall, so plan for around 19.4°C daytime highs and 13.3°C at night.
Not quite — December is the 9th coolest month in Whanganui, averaging 16.4°C.
For December in Whanganui, pack light layers you can adjust through the day, with typical highs of 19.4°C and lows of 13.3°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 79% — quite humid.
Average wind speed in December is 4.7 m/s. The windiest December on record averaged 5.9 m/s (1989).
The wettest December on record was 2021 with 232 mm. On average, December sees 87 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 Whanganui behaves each December, 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 December specifically, along with year-by-year records and how the month has changed over the decades.
