December is one of the cooler months of the year in Dorchester, with average highs near 9.9°C and lows around 7.4°C (mean 8.7°C). It is a relatively wet time of year, averaging 108 mm of rainfall and 86% relative humidity across the period.
December is one of the cooler months of the year in Dorchester. Across 45 years of records, the warmest December in Dorchester was 2015 — when the month averaged 12°C — while the coldest was 2010 at 4.4°C. Typical December days reach 9.9°C with nights near 7.4°C. The long-term trend is warming, about 0.3°C per decade.
December is a relatively wet time of year in Dorchester, averaging 108 mm of rainfall. The wettest December on record was 2020 with 202 mm, while the driest was 1991 at 34 mm.
Relative humidity in Dorchester during December averages 86%. The most humid December was 2002 at 90%, and the least humid was 1990 at 83%.
December receives about 0.6 kWh/m²/day of solar energy in Dorchester. The sunniest Decembers were 2001, 2008 and 2014 at 0.8 kWh/m²/day, and the cloudiest were 1998, 2002 and 2015 at 0.5.
Average wind speed in Dorchester during December is 6.9 m/s. The windiest December was 2015 at 8.7 m/s, while the calmest was 2016 at 4.9 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 8.5°C | 8.1°C | 8.4°C | 9.1°C | 9.4°C | +0.9°C |
| Avg High | 9.8°C | 9.4°C | 9.6°C | 10.3°C | 10.5°C | +0.7°C |
| Avg Low | 7.3°C | 6.8°C | 7.2°C | 7.9°C | 8.3°C | +1°C |
| Avg Rain | 105 mm | 104 mm | 94 mm | 114 mm | 135 mm | +30 mm |
December temperatures in Dorchester have risen by about 1.3°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -1.1°C (1996) to a record high of 14.2°C (2024).
Rainfall in December is a relatively wet time of year, averaging 108 mm, with a wettest year of 202 mm.
A quieter season to visit Dorchester
If your dates are flexible, the more temperate months of August and July tend to be the most comfortable for visiting Dorchester. That said, December — with days averaging 9.9°C and nights around 7.4°C (mean 8.7°C) and higher rainfall (108 mm) — can still be rewarding for travellers who don't mind the cooler conditions, and often means fewer crowds.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 10.8°C | 9.8°C | 8.8°C | 13.8°C | 4.0°C | 159 mm | 87% | 7.4 m/s | — |
| 2024 | 10.9°C | 9.8°C | 8.6°C | 14.2°C | 6.9°C | 67 mm | 88% | 6.8 m/s | 0.6 |
| 2023 | 11.3°C | 10.2°C | 9.1°C | 13.2°C | 3.1°C | 150 mm | 88% | 7.7 m/s | 0.6 |
| 2022 | 9.2°C | 8.1°C | 6.9°C | 13.1°C | 2.0°C | 127 mm | 87% | 6.4 m/s | 0.7 |
| 2021 | 10.9°C | 9.8°C | 8.7°C | 13.1°C | 5.7°C | 105 mm | 89% | 6.6 m/s | 0.6 |
| 2020 🌧️ | 9.7°C | 8.5°C | 7.4°C | 12.8°C | 3.4°C | 202 mm | 87% | 7 m/s | 0.7 |
| 2019 | 10.4°C | 9.3°C | 8.1°C | 12.7°C | 4.1°C | 171 mm | 86% | 6.9 m/s | 0.7 |
| 2018 | 11.3°C | 10.3°C | 9.3°C | 13.6°C | 5.6°C | 167 mm | 87% | 6.9 m/s | 0.6 |
| 2017 | 10.1°C | 8.7°C | 7.3°C | 13.1°C | 3.9°C | 133 mm | 87% | 7 m/s | 0.7 |
| 2016 | 10.9°C | 10.0°C | 9.0°C | 12.9°C | 6.2°C | 37 mm | 87% | 4.9 m/s | 0.7 |
| 2015 🔥 | 12.9°C | 12.0°C | 11.0°C | 13.8°C | 8.5°C | 116 mm | 87% | 8.7 m/s | 0.5 |
| 2014 | 10.1°C | 8.8°C | 7.5°C | 12.6°C | 3.8°C | 56 mm | 84% | 7.1 m/s | 0.8 |
| 2013 | 10.8°C | 9.5°C | 8.1°C | 12.5°C | 6.4°C | 121 mm | 84% | 7.3 m/s | 0.7 |
| 2012 | 9.9°C | 8.7°C | 7.4°C | 12.5°C | 3.7°C | 173 mm | 86% | 7.4 m/s | 0.7 |
| 2011 | 10.9°C | 9.6°C | 8.3°C | 13.6°C | 4.8°C | 112 mm | 85% | 7.9 m/s | 0.6 |
| 2010 ❄️ | 5.6°C | 4.4°C | 3.3°C | 9.3°C | 0.6°C | 52 mm | 88% | 5.8 m/s | 0.7 |
| 2009 | 8.8°C | 7.4°C | 6.1°C | 13.0°C | 1.5°C | 114 mm | 86% | 6.4 m/s | 0.7 |
| 2008 | 8.4°C | 7.3°C | 6.1°C | 11.7°C | 3.1°C | 61 mm | 87% | 6 m/s | 0.8 |
| 2007 | 10.3°C | 9.1°C | 8.0°C | 14.0°C | 5.0°C | 75 mm | 84% | 7.4 m/s | 0.6 |
| 2006 | 10.9°C | 9.8°C | 8.7°C | 14.0°C | 4.3°C | 103 mm | 85% | 7.4 m/s | 0.6 |
| 2005 | 9.3°C | 8.0°C | 6.7°C | 12.1°C | 1.1°C | 89 mm | 86% | 6 m/s | 0.7 |
| 2004 | 10.1°C | 8.8°C | 7.6°C | 12.6°C | 4.2°C | 71 mm | 87% | 5.6 m/s | 0.6 |
| 2003 | 9.7°C | 8.5°C | 7.3°C | 12.5°C | 3.5°C | 106 mm | 86% | 6.6 m/s | 0.6 |
| 2002 | 9.9°C | 8.8°C | 7.8°C | 12.9°C | 2.7°C | 119 mm | 90% | 6.9 m/s | 0.5 |
| 2001 | 8.7°C | 7.4°C | 6.0°C | 13.7°C | 2.4°C | 44 mm | 84% | 6.6 m/s | 0.8 |
| 2000 | 9.8°C | 8.9°C | 7.9°C | 12.9°C | 2.9°C | 154 mm | 88% | 7.7 m/s | 0.6 |
| 1999 | 10.0°C | 8.6°C | 7.2°C | 12.8°C | 2.4°C | 190 mm | 86% | 8.3 m/s | 0.6 |
| 1998 | 10.1°C | 8.8°C | 7.4°C | 12.9°C | 2.8°C | 110 mm | 88% | 6.7 m/s | 0.5 |
| 1997 | 10.5°C | 9.3°C | 8.2°C | 13.7°C | 3.4°C | 114 mm | 87% | 7.1 m/s | 0.6 |
| 1996 | 7.2°C | 6.0°C | 4.9°C | 12.3°C | -1.1°C | 43 mm | 88% | 6.5 m/s | 0.6 |
| 1995 | 8.4°C | 7.0°C | 5.5°C | 13.7°C | 1.2°C | 112 mm | 89% | 6.3 m/s | 0.6 |
| 1994 | 11.3°C | 10.1°C | 9.0°C | 13.8°C | 4.1°C | 109 mm | 85% | 7.6 m/s | 0.7 |
| 1993 | 9.8°C | 8.3°C | 6.9°C | 12.5°C | 2.3°C | 157 mm | 86% | 8.4 m/s | 0.7 |
| 1992 | 8.8°C | 7.5°C | 6.2°C | 13.1°C | 3.0°C | 97 mm | 87% | 6.5 m/s | 0.6 |
| 1991 | 9.3°C | 8.3°C | 7.3°C | 12.4°C | 3.8°C | 34 mm | 84% | 6.1 m/s | 0.7 |
| 1990 | 8.5°C | 7.2°C | 5.8°C | 11.6°C | 2.3°C | 72 mm | 83% | 7 m/s | 0.7 |
| 1989 | 10.3°C | 9.1°C | 8.0°C | 13.4°C | 4.3°C | 153 mm | 87% | 7.4 m/s | 0.7 |
| 1988 | 10.5°C | 9.4°C | 8.2°C | 12.5°C | 3.5°C | 35 mm | 88% | 5.4 m/s | 0.6 |
| 1987 | 9.5°C | 8.6°C | 7.7°C | 12.7°C | 3.4°C | 63 mm | 89% | 7.3 m/s | 0.6 |
| 1986 | 10.1°C | 8.7°C | 7.4°C | 13.1°C | 2.9°C | 115 mm | 86% | 7.8 m/s | 0.6 |
| 1985 | 10.4°C | 9.4°C | 8.4°C | 13.9°C | 1.2°C | 132 mm | 87% | 6.5 m/s | 0.6 |
| 1984 | 10.1°C | 8.9°C | 7.6°C | 12.4°C | 4.4°C | 120 mm | 86% | 5.4 m/s | 0.7 |
| 1983 | 10.0°C | 8.9°C | 7.7°C | 12.2°C | 3.5°C | 89 mm | 84% | 6.9 m/s | — |
| 1982 | 9.2°C | 7.8°C | 6.4°C | 12.8°C | 3.0°C | 113 mm | 85% | 6.7 m/s | — |
| 1981 | 7.7°C | 6.0°C | 4.4°C | 11.1°C | 0.8°C | 126 mm | 86% | 6.6 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 9.9°C with lows near 7.4°C (mean 8.7°C), based on 45 years of NASA POWER data.
December averages 108 mm of rainfall in Dorchester, a relatively wet time of year. The wettest on record was 202 mm in 2020.
The hottest December reached 14.2°C in 2024. The coldest dipped to -1.1°C in 1996.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 1.3°C. Daytime highs moved from 9.5°C to 10.6°C and overnight lows from 6.9°C to 8.4°C over the same span.
December is one of the cooler months of the year in Dorchester and a relatively wet time of year, so plan for around 9.9°C daytime highs and 7.4°C at night.
Not quite — December is the 4th coolest month in Dorchester, averaging 8.7°C.
For December in Dorchester, pack warm layers and a jacket for chilly mornings, with typical highs of 9.9°C and lows of 7.4°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 86% — quite humid.
Average wind speed in December is 6.9 m/s. The windiest December on record averaged 8.7 m/s (2015).
The wettest December on record was 2020 with 202 mm. On average, December sees 108 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 Dorchester 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.
