December is one of the cooler months of the year in Hilo, with average highs near 22.8°C and lows around 19.2°C (mean 21°C). It is about average for rainfall, averaging 155 mm of rainfall and 82% relative humidity across the period.
December is one of the cooler months of the year in Hilo. Across 45 years of records, the warmest December in Hilo was 1995 — when the month averaged 22.6°C — while the coldest was 1984 at 20.1°C. Typical December days reach 22.8°C with nights near 19.2°C. The long-term December temperature trend is broadly flat.
December is about average for rainfall in Hilo, averaging 155 mm of rainfall. The wettest December on record was 2001 with 692 mm, while the driest was 1994 at 4 mm.
Relative humidity in Hilo during December averages 82%. The most humid December was 2016 at 87%, and the least humid was 1994 at 74%.
December receives about 4.1 kWh/m²/day of solar energy in Hilo. The sunniest December was 2024 at 4.7 kWh/m²/day, and the cloudiest was 2016 at 3.1.
Average wind speed in Hilo during December is 4 m/s. The windiest December was 2007 at 5.3 m/s, while the calmest was 1983 at 2.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 20.9°C | 21.0°C | 20.9°C | 21.0°C | 21.4°C | +0.5°C |
| Avg High | 22.8°C | 22.9°C | 22.6°C | 22.6°C | 23.2°C | +0.4°C |
| Avg Low | 19.0°C | 19.1°C | 19.2°C | 19.3°C | 19.6°C | +0.6°C |
| Avg Rain | 156 mm | 35 mm | 303 mm | 135 mm | 140 mm | -16 mm |
December temperatures in Hilo have risen by about 0.7°C between 1981–1985 and 2021–2025.
December has ranged from a record low of 16.1°C (1982) to a record high of 27.7°C (1996).
Rainfall in December is about average for rainfall, averaging 155 mm, with a wettest year of 692 mm.
A good time to visit Hilo
December is a good time to visit Hilo, with days averaging 22.8°C and nights around 19.2°C (mean 21°C, close to Hilo's yearly average) and higher rainfall. June and May are marginally more temperate, but December still suits most travellers.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 23.4°C | 21.5°C | 19.5°C | 25.4°C | 18.5°C | 134 mm | 83% | 3.4 m/s | — |
| 2024 | 23.9°C | 21.9°C | 19.8°C | 25.6°C | 18.4°C | 56 mm | 83% | 3.4 m/s | 4.7 |
| 2023 | 22.8°C | 21.1°C | 19.3°C | 24.9°C | 18.1°C | 158 mm | 84% | 3.8 m/s | 4.4 |
| 2022 | 23.8°C | 21.8°C | 19.8°C | 25.8°C | 18.9°C | 115 mm | 82% | 3.7 m/s | 4.2 |
| 2021 | 22.1°C | 20.7°C | 19.4°C | 25.6°C | 17.8°C | 316 mm | 86% | 3.9 m/s | 3.6 |
| 2020 | 23.4°C | 21.6°C | 19.7°C | 25.2°C | 18.6°C | 60 mm | 83% | 3.5 m/s | 4.3 |
| 2019 | 23.4°C | 21.8°C | 20.2°C | 25.7°C | 19.3°C | 102 mm | 85% | 3.9 m/s | 4 |
| 2018 | 22.7°C | 21.2°C | 19.7°C | 25.2°C | 18.4°C | 118 mm | 85% | 4.3 m/s | 4.3 |
| 2017 | 22.7°C | 20.5°C | 18.4°C | 25.6°C | 17.0°C | 101 mm | 81% | 3.6 m/s | 4.2 |
| 2016 | 22.4°C | 20.9°C | 19.4°C | 24.3°C | 18.4°C | 301 mm | 87% | 3.2 m/s | 3.1 |
| 2015 | 22.9°C | 21.3°C | 19.7°C | 24.4°C | 18.6°C | 76 mm | 84% | 4.1 m/s | 4.4 |
| 2014 | 22.9°C | 20.9°C | 18.9°C | 25.4°C | 17.1°C | 133 mm | 82% | 3.4 m/s | 4.2 |
| 2013 | 22.9°C | 21.2°C | 19.5°C | 24.6°C | 18.6°C | 152 mm | 85% | 3.4 m/s | 3.9 |
| 2012 | 22.2°C | 20.6°C | 19.0°C | 24.6°C | 17.8°C | 82 mm | 84% | 4.2 m/s | 4.1 |
| 2011 | 21.5°C | 20.2°C | 18.9°C | 23.9°C | 17.5°C | 139 mm | 86% | 4.8 m/s | 3.8 |
| 2010 | 22.7°C | 21.0°C | 19.2°C | 23.8°C | 18.1°C | 142 mm | 84% | 3.3 m/s | 3.9 |
| 2009 | 23.5°C | 21.5°C | 19.4°C | 25.7°C | 18.0°C | 98 mm | 82% | 3.1 m/s | 4.5 |
| 2008 | 21.7°C | 20.3°C | 19.0°C | 23.8°C | 18.1°C | 440 mm | 87% | 4.1 m/s | 3.6 |
| 2007 | 22.3°C | 21.1°C | 19.8°C | 26.0°C | 18.5°C | 535 mm | 86% | 5.3 m/s | 3.5 |
| 2006 | 22.4°C | 20.8°C | 19.2°C | 24.1°C | 18.2°C | 209 mm | 84% | 4.1 m/s | 4.3 |
| 2005 | 23.0°C | 21.0°C | 19.0°C | 25.6°C | 17.6°C | 162 mm | 83% | 3.3 m/s | 4.5 |
| 2004 | 22.5°C | 20.8°C | 19.1°C | 25.1°C | 17.6°C | 255 mm | 84% | 4.3 m/s | 4.1 |
| 2003 | 22.5°C | 20.9°C | 19.3°C | 24.9°C | 17.6°C | 311 mm | 85% | 4 m/s | 4 |
| 2002 | 22.2°C | 20.4°C | 18.7°C | 23.6°C | 17.4°C | 300 mm | 83% | 4 m/s | 4.3 |
| 2001 🌧️ | 22.4°C | 20.8°C | 19.3°C | 25.7°C | 17.8°C | 692 mm | 83% | 4.6 m/s | 4.2 |
| 2000 | 23.1°C | 21.0°C | 18.8°C | 24.7°C | 17.9°C | 28 mm | 80% | 3.7 m/s | 4.5 |
| 1999 | 22.9°C | 20.9°C | 18.9°C | 25.1°C | 17.0°C | 16 mm | 81% | 4.2 m/s | 4 |
| 1998 | 22.1°C | 20.4°C | 18.7°C | 24.7°C | 17.5°C | 40 mm | 80% | 4.5 m/s | 4.1 |
| 1997 | 22.3°C | 20.5°C | 18.8°C | 24.5°C | 17.5°C | 7 mm | 76% | 4.9 m/s | 4.3 |
| 1996 | 23.7°C | 21.5°C | 19.2°C | 27.7°C | 17.7°C | 9 mm | 77% | 4.6 m/s | 4 |
| 1995 🔥 | 25.0°C | 22.6°C | 20.1°C | 27.2°C | 17.9°C | 7 mm | 77% | 3.8 m/s | 4.3 |
| 1994 | 22.0°C | 20.2°C | 18.3°C | 23.7°C | 16.7°C | 4 mm | 74% | 4.9 m/s | 4.4 |
| 1993 | 22.4°C | 20.6°C | 18.8°C | 24.3°C | 17.6°C | 8 mm | 75% | 5 m/s | 4.2 |
| 1992 | 23.3°C | 21.6°C | 19.8°C | 25.8°C | 18.9°C | 13 mm | 80% | 4.8 m/s | 3.7 |
| 1991 | 22.5°C | 20.9°C | 19.4°C | 25.1°C | 17.4°C | 10 mm | 80% | 4.9 m/s | 3.8 |
| 1990 | 22.5°C | 20.8°C | 19.1°C | 25.0°C | 17.2°C | 239 mm | 83% | 4.2 m/s | 3.3 |
| 1989 | 23.9°C | 21.5°C | 19.0°C | 25.5°C | 16.8°C | 29 mm | 77% | 3.4 m/s | 3.6 |
| 1988 | 23.4°C | 21.5°C | 19.6°C | 25.9°C | 17.7°C | 28 mm | 79% | 4.1 m/s | 3.9 |
| 1987 | 22.8°C | 21.2°C | 19.7°C | 23.9°C | 18.3°C | 75 mm | 85% | 4.3 m/s | 3.8 |
| 1986 | 22.7°C | 20.8°C | 19.0°C | 23.8°C | 17.7°C | 110 mm | 82% | 3.7 m/s | 4.2 |
| 1985 | 22.7°C | 20.9°C | 19.0°C | 25.0°C | 17.0°C | 246 mm | 84% | 3.6 m/s | 4.2 |
| 1984 ❄️ | 21.7°C | 20.1°C | 18.4°C | 23.6°C | 16.5°C | 14 mm | 83% | 4 m/s | 3.9 |
| 1983 | 23.4°C | 21.2°C | 19.0°C | 25.4°C | 16.3°C | 429 mm | 82% | 2.7 m/s | — |
| 1982 | 22.0°C | 20.2°C | 18.3°C | 24.4°C | 16.1°C | 429 mm | 84% | 3.8 m/s | — |
| 1981 | 23.0°C | 21.0°C | 19.0°C | 26.3°C | 16.8°C | 46 mm | 81% | 4.1 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 22.8°C with lows near 19.2°C (mean 21°C), based on 45 years of NASA POWER data.
December averages 155 mm of rainfall in Hilo, about average for rainfall. The wettest on record was 692 mm in 2001.
The hottest December reached 27.7°C in 1996. The coldest dipped to 16.1°C in 1982.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 0.7°C. Daytime highs moved from 22.6°C to 23.2°C and overnight lows from 18.7°C to 19.6°C over the same span.
December is one of the cooler months of the year in Hilo and about average for rainfall, so plan for around 22.8°C daytime highs and 19.2°C at night.
Not quite — December is the 5th coolest month in Hilo, averaging 21°C.
For December in Hilo, pack light layers you can adjust through the day, with typical highs of 22.8°C and lows of 19.2°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 82% — quite humid.
Average wind speed in December is 4 m/s. The windiest December on record averaged 5.3 m/s (2007).
The wettest December on record was 2001 with 692 mm. On average, December sees 155 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 Hilo 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.
