December is one of the warmer months of the year in Blenheim, with average highs near 19.1°C and lows around 9.7°C (mean 14.4°C). It is about average for rainfall, averaging 72 mm of rainfall and 76% relative humidity across the period.
December is one of the warmer months of the year in Blenheim. Across 45 years of records, the warmest December in Blenheim was 2017 — when the month averaged 16.7°C — while the coldest was 2004 at 12°C. Typical December days reach 19.1°C with nights near 9.7°C. The long-term trend is warming, about 0.2°C per decade.
December is about average for rainfall in Blenheim, averaging 72 mm of rainfall. The wettest December on record was 2011 with 200 mm, while the driest was 1994 at 25 mm.
Relative humidity in Blenheim during December averages 76%. The most humid December was 2021 at 85%, and the least humid was 1997 at 66%.
December receives about 6.4 kWh/m²/day of solar energy in Blenheim. The sunniest December was 2017 at 7.5 kWh/m²/day, and the cloudiest was 2001 at 5.4.
Average wind speed in Blenheim during December is 2.5 m/s. The windiest December was 1997 at 2.9 m/s, while the calmest were 2018 and 2022 at 1.9 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 14.3°C | 13.8°C | 14.5°C | 14.8°C | 14.7°C | +0.4°C |
| Avg High | 19.0°C | 18.6°C | 19.5°C | 19.5°C | 19.0°C | 0°C |
| Avg Low | 9.7°C | 9.0°C | 9.6°C | 10.0°C | 10.3°C | +0.6°C |
| Avg Rain | 76 mm | 66 mm | 56 mm | 83 mm | 87 mm | +12 mm |
December temperatures in Blenheim have risen by about 0.5°C between 1981–1985 and 2021–2025.
December has ranged from a record low of 2.3°C (2006) to a record high of 28.6°C (2015).
Rainfall in December is about average for rainfall, averaging 72 mm, with a wettest year of 200 mm.
One of the best times to visit Blenheim
December is one of the best times to visit Blenheim. Expect days averaging 19.1°C and nights around 9.7°C (mean 14.4°C) — warmer than Blenheim's yearly average — with moderate rainfall (72 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 | 18.8°C | 14.3°C | 9.8°C | 24.5°C | 6.2°C | 75 mm | 76% | 2.8 m/s | — |
| 2024 | 20.1°C | 15.4°C | 10.7°C | 23.7°C | 5.5°C | 72 mm | 79% | 2.6 m/s | 6.9 |
| 2023 | 19.7°C | 15.2°C | 10.7°C | 25.1°C | 6.1°C | 65 mm | 79% | 2.6 m/s | 6.3 |
| 2022 | 18.2°C | 14.3°C | 10.5°C | 23.3°C | 6.3°C | 86 mm | 84% | 1.9 m/s | 6.6 |
| 2021 | 19.0°C | 15.1°C | 11.2°C | 22.1°C | 8.3°C | 153 mm | 85% | 2.4 m/s | 5.9 |
| 2020 | 18.4°C | 13.7°C | 9.0°C | 24.4°C | 5.0°C | 73 mm | 79% | 2.5 m/s | 6.5 |
| 2019 | 18.2°C | 13.7°C | 9.2°C | 21.9°C | 5.3°C | 115 mm | 79% | 2.8 m/s | 6.4 |
| 2018 | 19.5°C | 15.1°C | 10.8°C | 26.1°C | 6.5°C | 96 mm | 81% | 1.9 m/s | 6 |
| 2017 🔥 | 22.1°C | 16.7°C | 11.3°C | 26.5°C | 6.8°C | 37 mm | 71% | 2.4 m/s | 7.5 |
| 2016 | 17.4°C | 13.0°C | 8.6°C | 21.6°C | 5.9°C | 71 mm | 81% | 2.4 m/s | 6.6 |
| 2015 | 20.4°C | 14.6°C | 8.9°C | 28.6°C | 4.1°C | 37 mm | 70% | 2.1 m/s | 7.1 |
| 2014 | 19.8°C | 15.0°C | 10.2°C | 24.0°C | 3.2°C | 83 mm | 75% | 2.3 m/s | 6.1 |
| 2013 | 19.6°C | 15.1°C | 10.5°C | 23.1°C | 6.0°C | 54 mm | 76% | 2.4 m/s | 6.3 |
| 2012 | 20.7°C | 15.5°C | 10.4°C | 26.8°C | 6.1°C | 43 mm | 73% | 2.7 m/s | 6.6 |
| 2011 🌧️ | 17.5°C | 13.7°C | 9.8°C | 21.2°C | 5.5°C | 200 mm | 82% | 2.2 m/s | 5.8 |
| 2010 | 20.0°C | 15.2°C | 10.3°C | 23.6°C | 6.3°C | 97 mm | 76% | 2.5 m/s | 6.1 |
| 2009 | 19.4°C | 14.2°C | 9.0°C | 24.7°C | 5.7°C | 49 mm | 73% | 2.6 m/s | 6.6 |
| 2008 | 19.2°C | 14.5°C | 9.8°C | 25.0°C | 6.8°C | 76 mm | 76% | 2.4 m/s | 6.1 |
| 2007 | 19.4°C | 14.7°C | 10.0°C | 25.3°C | 5.3°C | 58 mm | 74% | 2.6 m/s | 5.9 |
| 2006 | 18.0°C | 12.6°C | 7.2°C | 24.0°C | 2.3°C | 42 mm | 70% | 2.3 m/s | 6.8 |
| 2005 | 21.4°C | 16.5°C | 11.7°C | 26.7°C | 8.5°C | 48 mm | 73% | 2.3 m/s | 6.2 |
| 2004 ❄️ | 16.6°C | 12.0°C | 7.3°C | 20.3°C | 3.7°C | 90 mm | 74% | 2.5 m/s | 6.3 |
| 2003 | 20.9°C | 15.1°C | 9.4°C | 24.9°C | 5.2°C | 30 mm | 71% | 2.8 m/s | 6.9 |
| 2002 | 19.2°C | 14.4°C | 9.7°C | 25.9°C | 4.2°C | 76 mm | 73% | 2.7 m/s | 6.4 |
| 2001 | 19.2°C | 15.1°C | 11.1°C | 25.0°C | 6.5°C | 61 mm | 78% | 2.8 m/s | 5.4 |
| 2000 | 21.7°C | 16.2°C | 10.7°C | 26.0°C | 6.5°C | 28 mm | 68% | 2.7 m/s | 6.9 |
| 1999 | 19.2°C | 13.8°C | 8.4°C | 25.5°C | 3.5°C | 37 mm | 71% | 2.3 m/s | 6.7 |
| 1998 | 19.2°C | 14.6°C | 10.1°C | 25.8°C | 5.5°C | 52 mm | 76% | 2.6 m/s | 6.5 |
| 1997 | 19.9°C | 14.3°C | 8.8°C | 23.3°C | 3.7°C | 27 mm | 66% | 2.9 m/s | 6.5 |
| 1996 | 18.4°C | 13.3°C | 8.2°C | 23.2°C | 4.0°C | 65 mm | 75% | 2.4 m/s | 6.9 |
| 1995 | 19.0°C | 14.8°C | 10.6°C | 24.6°C | 6.2°C | 78 mm | 80% | 2.8 m/s | 6.5 |
| 1994 | 19.6°C | 14.4°C | 9.2°C | 23.4°C | 5.2°C | 25 mm | 73% | 2.2 m/s | 7.1 |
| 1993 | 17.2°C | 12.6°C | 8.0°C | 23.1°C | 4.5°C | 123 mm | 81% | 2.1 m/s | 6 |
| 1992 | 16.3°C | 12.5°C | 8.7°C | 21.4°C | 3.4°C | 108 mm | 83% | 2.2 m/s | 5.6 |
| 1991 | 18.1°C | 13.3°C | 8.5°C | 24.1°C | 4.1°C | 114 mm | 78% | 2 m/s | 6.2 |
| 1990 | 19.0°C | 14.1°C | 9.2°C | 23.1°C | 4.5°C | 35 mm | 76% | 2.6 m/s | 6.8 |
| 1989 | 18.5°C | 13.5°C | 8.6°C | 22.6°C | 5.0°C | 40 mm | 73% | 2.8 m/s | 6.4 |
| 1988 | 21.2°C | 16.0°C | 10.7°C | 26.1°C | 5.4°C | 32 mm | 71% | 2.3 m/s | 7.1 |
| 1987 | 17.8°C | 13.7°C | 9.6°C | 22.0°C | 4.8°C | 87 mm | 80% | 2.4 m/s | 6.1 |
| 1986 | 18.4°C | 13.7°C | 8.9°C | 23.2°C | 3.1°C | 70 mm | 77% | 2.3 m/s | 6.7 |
| 1985 | 18.3°C | 14.3°C | 10.4°C | 22.4°C | 5.2°C | 134 mm | 82% | 2.2 m/s | 5.9 |
| 1984 | 19.9°C | 15.3°C | 10.7°C | 24.9°C | 8.1°C | 115 mm | 76% | 2.5 m/s | 5.7 |
| 1983 | 17.6°C | 13.0°C | 8.4°C | 23.0°C | 5.2°C | 92 mm | 76% | 2.5 m/s | — |
| 1982 | 19.4°C | 13.9°C | 8.4°C | 28.3°C | 3.4°C | 64 mm | 66% | 2.6 m/s | — |
| 1981 | 19.7°C | 15.6°C | 11.4°C | 23.7°C | 6.0°C | 47 mm | 79% | 2.6 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 19.1°C with lows near 9.7°C (mean 14.4°C), based on 45 years of NASA POWER data.
December averages 72 mm of rainfall in Blenheim, about average for rainfall. The wettest on record was 200 mm in 2011.
The hottest December reached 28.6°C in 2015. The coldest dipped to 2.3°C in 2006.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 0.5°C. Daytime highs moved from 19°C to 19.2°C and overnight lows from 9.9°C to 10.6°C over the same span.
December is one of the warmer months of the year in Blenheim and about average for rainfall, so plan for around 19.1°C daytime highs and 9.7°C at night.
Not quite — December is the 9th coolest month in Blenheim, averaging 14.4°C.
For December in Blenheim, pack light layers you can adjust through the day, with typical highs of 19.1°C and lows of 9.7°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 76% — quite humid.
Average wind speed in December is 2.5 m/s. The windiest December on record averaged 2.9 m/s (1997).
The wettest December on record was 2011 with 200 mm. On average, December sees 72 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 Blenheim 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.
