January is one of the cooler months of the year in Mililani, with average highs near 24.2°C and lows around 21.6°C (mean 22.9°C). It is a relatively wet time of year, averaging 87 mm of rainfall and 75% relative humidity across the period.
January is one of the cooler months of the year in Mililani. Across 45 years of records, the warmest Januarys in Mililani were 2021 and 2025 — when the month averaged 24.1°C — while the coldest were 1983 and 1986 at 21.9°C. Typical January days reach 24.2°C with nights near 21.6°C. The long-term trend is warming, about 0.3°C per decade.
January is a relatively wet time of year in Mililani, averaging 87 mm of rainfall. The wettest January on record was 1983 with 488 mm, while the driest was 2010 at 6 mm.
Relative humidity in Mililani during January averages 75%. The most humid January was 1984 at 82%, and the least humid was 1993 at 69%.
January receives about 4.1 kWh/m²/day of solar energy in Mililani. The sunniest Januarys were 2001, 2016 and 2022 at 4.5 kWh/m²/day, and the cloudiest was 1990 at 3.4.
Average wind speed in Mililani during January is 4.7 m/s. The windiest January was 2000 at 6.6 m/s, while the calmest was 2016 at 2.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 22.4°C | 22.5°C | 23.0°C | 23.1°C | 23.8°C | +1.4°C |
| Avg High | 23.6°C | 23.8°C | 24.3°C | 24.5°C | 25.2°C | +1.6°C |
| Avg Low | 21.2°C | 21.2°C | 21.7°C | 21.7°C | 22.5°C | +1.3°C |
| Avg Rain | 180 mm | 48 mm | 79 mm | 52 mm | 83 mm | -96 mm |
January temperatures in Mililani have risen by about 1.4°C between 1981–1985 and 2021–2025.
January has ranged from a record low of 17.4°C (1985) to a record high of 27.1°C (2025).
Rainfall in January is a relatively wet time of year, averaging 87 mm, with a wettest year of 488 mm.
One of the best times to visit Mililani
January is one of the best times to visit Mililani. Expect days averaging 24.2°C and nights around 21.6°C (mean 22.9°C) — cooler than Mililani'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 | 25.7°C | 24.1°C | 22.5°C | 27.1°C | 20.2°C | 45 mm | 74% | 4.7 m/s | 4.3 |
| 2024 | 25.2°C | 23.8°C | 22.3°C | 26.2°C | 19.0°C | 37 mm | 77% | 4.4 m/s | 4.2 |
| 2023 | 25.3°C | 23.8°C | 22.3°C | 26.6°C | 20.6°C | 68 mm | 77% | 3.6 m/s | 4.2 |
| 2022 | 24.9°C | 23.6°C | 22.3°C | 25.8°C | 21.6°C | 81 mm | 78% | 2.9 m/s | 4.5 |
| 2021 🔥 | 25.4°C | 24.1°C | 22.9°C | 26.5°C | 21.5°C | 139 mm | 77% | 5.8 m/s | 4.2 |
| 2020 | 24.8°C | 23.7°C | 22.6°C | 26.0°C | 21.3°C | 130 mm | 78% | 5.8 m/s | 4 |
| 2019 | 24.5°C | 23.1°C | 21.8°C | 25.7°C | 19.5°C | 49 mm | 74% | 4.4 m/s | 4.4 |
| 2018 | 24.7°C | 23.3°C | 22.0°C | 25.4°C | 21.1°C | 49 mm | 77% | 4.8 m/s | 4.4 |
| 2017 | 24.3°C | 22.9°C | 21.4°C | 26.1°C | 19.7°C | 25 mm | 74% | 4.2 m/s | 4.3 |
| 2016 | 25.2°C | 23.7°C | 22.3°C | 26.4°C | 21.3°C | 25 mm | 74% | 2.7 m/s | 4.5 |
| 2015 | 24.3°C | 22.7°C | 21.2°C | 26.1°C | 19.3°C | 52 mm | 74% | 3.4 m/s | 4.3 |
| 2014 | 24.4°C | 22.9°C | 21.5°C | 25.8°C | 19.2°C | 73 mm | 75% | 4.1 m/s | 4.3 |
| 2013 | 24.1°C | 22.7°C | 21.3°C | 25.1°C | 19.6°C | 99 mm | 77% | 5.2 m/s | 4.1 |
| 2012 | 24.8°C | 23.4°C | 22.0°C | 25.9°C | 21.1°C | 23 mm | 76% | 4.1 m/s | 4.4 |
| 2011 | 24.3°C | 23.0°C | 21.6°C | 25.7°C | 19.7°C | 119 mm | 74% | 4.3 m/s | 4.2 |
| 2010 | 24.8°C | 23.2°C | 21.7°C | 26.1°C | 19.5°C | 6 mm | 74% | 4.2 m/s | 4.3 |
| 2009 | 24.0°C | 22.7°C | 21.4°C | 25.1°C | 19.4°C | 36 mm | 75% | 4.8 m/s | 4.2 |
| 2008 | 23.9°C | 22.7°C | 21.5°C | 25.6°C | 20.4°C | 17 mm | 73% | 6.1 m/s | 4.3 |
| 2007 | 24.9°C | 23.7°C | 22.4°C | 26.0°C | 21.4°C | 24 mm | 74% | 5.5 m/s | 4.3 |
| 2006 | 24.9°C | 23.6°C | 22.2°C | 25.9°C | 20.5°C | 68 mm | 75% | 6.3 m/s | 4.3 |
| 2005 | 24.5°C | 23.2°C | 21.9°C | 25.5°C | 19.4°C | 155 mm | 79% | 4.3 m/s | 4 |
| 2004 | 24.3°C | 23.0°C | 21.8°C | 25.3°C | 20.4°C | 208 mm | 79% | 4.7 m/s | 4.1 |
| 2003 | 24.1°C | 22.5°C | 21.0°C | 25.6°C | 18.9°C | 76 mm | 73% | 4.7 m/s | 4.2 |
| 2002 | 24.2°C | 22.9°C | 21.6°C | 26.0°C | 20.0°C | 158 mm | 78% | 5.5 m/s | 4 |
| 2001 | 25.1°C | 23.7°C | 22.3°C | 26.4°C | 21.4°C | 35 mm | 74% | 5 m/s | 4.5 |
| 2000 | 23.3°C | 22.1°C | 20.8°C | 24.9°C | 19.7°C | 15 mm | 73% | 6.6 m/s | 4.2 |
| 1999 | 24.0°C | 22.6°C | 21.3°C | 25.0°C | 20.4°C | 30 mm | 76% | 5.6 m/s | 4.2 |
| 1998 | 24.2°C | 22.7°C | 21.2°C | 25.5°C | 19.4°C | 31 mm | 69% | 3.6 m/s | 4.1 |
| 1997 | 23.6°C | 22.2°C | 20.9°C | 25.1°C | 18.3°C | 33 mm | 78% | 5 m/s | 4 |
| 1996 | 24.8°C | 23.5°C | 22.1°C | 26.5°C | 19.8°C | 60 mm | 75% | 4.1 m/s | 3.9 |
| 1995 | 23.8°C | 22.5°C | 21.1°C | 25.0°C | 19.7°C | 15 mm | 72% | 4.8 m/s | 3.9 |
| 1994 | 23.3°C | 22.0°C | 20.7°C | 25.5°C | 18.8°C | 19 mm | 72% | 5.1 m/s | 3.9 |
| 1993 | 23.7°C | 22.2°C | 20.8°C | 25.6°C | 19.4°C | 21 mm | 69% | 5.1 m/s | 3.8 |
| 1992 | 23.8°C | 22.4°C | 21.0°C | 25.1°C | 19.0°C | 35 mm | 72% | 4.1 m/s | 4.1 |
| 1991 | 23.1°C | 22.0°C | 20.9°C | 25.0°C | 19.0°C | 166 mm | 76% | 4.3 m/s | 4 |
| 1990 | 23.7°C | 22.6°C | 21.6°C | 25.1°C | 20.0°C | 74 mm | 79% | 6 m/s | 3.4 |
| 1989 | 24.1°C | 23.0°C | 21.9°C | 25.5°C | 20.6°C | 71 mm | 77% | 5.7 m/s | 3.9 |
| 1988 | 23.7°C | 22.6°C | 21.4°C | 25.5°C | 19.6°C | 112 mm | 78% | 5 m/s | 3.8 |
| 1987 | 23.4°C | 22.1°C | 20.8°C | 25.8°C | 18.7°C | 187 mm | 74% | 5.5 m/s | 3.6 |
| 1986 | 23.2°C | 21.9°C | 20.7°C | 24.7°C | 18.6°C | 98 mm | 78% | 4.3 m/s | 4 |
| 1985 | 23.4°C | 22.1°C | 20.7°C | 24.7°C | 17.4°C | 145 mm | 75% | 3.6 m/s | 3.9 |
| 1984 | 23.5°C | 22.5°C | 21.6°C | 24.4°C | 20.5°C | 248 mm | 82% | 4.6 m/s | 3.9 |
| 1983 ❄️ 🌧️ | 22.9°C | 21.9°C | 20.8°C | 24.1°C | 18.4°C | 488 mm | 77% | 4.1 m/s | — |
| 1982 | 23.5°C | 22.4°C | 21.4°C | 25.4°C | 18.4°C | 210 mm | 79% | 4.4 m/s | — |
| 1981 | 24.8°C | 23.4°C | 21.9°C | 26.0°C | 18.7°C | 58 mm | 75% | 3.6 m/s | — |
Actual recorded January data for each year, 1981–2025 — sourced from NASA POWER.
The average high in January is around 24.2°C with lows near 21.6°C (mean 22.9°C), based on 45 years of NASA POWER data.
January averages 87 mm of rainfall in Mililani, a relatively wet time of year. The wettest on record was 488 mm in 1983.
The hottest January reached 27.1°C in 2025. The coldest dipped to 17.4°C in 1985.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average January temperatures have risen by about 1.4°C. Daytime highs moved from 23.6°C to 25.3°C and overnight lows from 21.3°C to 22.5°C over the same span.
January is one of the cooler months of the year in Mililani and a relatively wet time of year, so plan for around 24.2°C daytime highs and 21.6°C at night.
Not quite — January is the 2nd coolest month in Mililani, averaging 22.9°C.
For January in Mililani, pack light layers you can adjust through the day, with typical highs of 24.2°C and lows of 21.6°C. Bring an umbrella or light rain jacket too.
Relative humidity in January averages 75% — quite humid.
Average wind speed in January is 4.7 m/s. The windiest January on record averaged 6.6 m/s (2000).
The wettest January on record was 1983 with 488 mm. On average, January 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 Mililani behaves each January, 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 January specifically, along with year-by-year records and how the month has changed over the decades.
