December is one of the cooler months of the year in Upper Siang, with average highs near 21.5°C and lows around 1.7°C (mean 11.6°C). It is one of the drier months, averaging 9 mm of rainfall and 74% relative humidity across the period.
December is one of the cooler months of the year in Upper Siang. Across 45 years of records, the warmest December in Upper Siang was 2016 — when the month averaged 15°C — while the coldest was 1982 at 8.6°C. Typical December days reach 21.5°C with nights near 1.7°C. The long-term December temperature trend is broadly flat.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 11.3°C | 11.7°C | 12.0°C | 11.7°C | 11.1°C | -0.2°C |
| Avg High | 21.5°C | 22.2°C | 22.0°C | 21.6°C | 19.8°C | -1.7°C |
| Avg Low | 1.0°C | 1.3°C | 2.0°C | 1.9°C | 2.4°C | +1.4°C |
| Avg Rain | 18 mm | 7 mm | 4 mm | 7 mm | 11 mm | -7 mm |
December temperatures in Upper Siang have risen by about 0.9°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -1.3°C (1986) to a record high of 26.4°C (2016).
Rainfall in December is one of the drier months, averaging 9 mm, with a wettest year of 61 mm.
Daytime highs and overnight lows have shifted differently — highs fell about 0.3°C per decade while lows rose 0.3°C per decade, narrowing the gap between day and night.
A quieter season to visit Upper Siang
If your dates are flexible, the more temperate months of October and November tend to be the most comfortable for visiting Upper Siang. That said, December — with days averaging 21.5°C and nights around 1.7°C (mean 11.6°C) and low rainfall (9 mm) — can still be rewarding for travellers who don't mind the cooler conditions, and often means fewer crowds.
| Year | High | Low | Avg | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|
| 2025 | 22.5°C | 3.8°C | 13.2°C | 5 mm | 75% | 0.5 m/s | — |
| 2024 | 17.8°C | 2.4°C | 10.1°C | 1 mm | 74% | 0.5 m/s | 3.4 |
| 2023 | 21.5°C | 2.9°C | 12.2°C | 12 mm | 77% | 0.5 m/s | 3.2 |
| 2022 | 19.0°C | 1.2°C | 10.1°C | 24 mm | 81% | 0.4 m/s | 2.8 |
| 2021 | 20.0°C | 1.3°C | 10.6°C | 13 mm | 78% | 0.5 m/s | 3.2 |
| 2020 | 18.0°C | 3.0°C | 10.5°C | 11 mm | 81% | 0.4 m/s | 3.2 |
| 2019 | 20.1°C | 0.3°C | 10.2°C | 3 mm | 78% | 0.4 m/s | 3 |
| 2018 | 20.2°C | 1.8°C | 11.0°C | 14 mm | 75% | 0.5 m/s | 3.4 |
| 2017 | 20.9°C | 3.3°C | 12.1°C | 1 mm | 79% | 0.5 m/s | 3.6 |
| 2016 🔥 | 26.4°C | 3.5°C | 15.0°C | 7 mm | 74% | 0.5 m/s | 3.5 |
| 2015 | 18.5°C | 1.0°C | 9.8°C | 12 mm | 81% | 0.4 m/s | 2.8 |
| 2014 | 22.6°C | 2.7°C | 12.6°C | 1 mm | 78% | 0.4 m/s | 3.1 |
| 2013 | 23.3°C | 0.4°C | 11.8°C | 5 mm | 78% | 0.4 m/s | 3 |
| 2012 | 19.1°C | 2.9°C | 11.0°C | 10 mm | 81% | 0.4 m/s | 3 |
| 2011 | 23.0°C | 1.7°C | 12.3°C | 17 mm | 76% | 0.5 m/s | 3.2 |
| 2010 | 21.6°C | 1.2°C | 11.4°C | 3 mm | 70% | 0.5 m/s | 3.7 |
| 2009 | 20.5°C | 1.7°C | 11.1°C | 6 mm | 79% | 0.5 m/s | 2.7 |
| 2008 | 24.3°C | 1.7°C | 13.0°C | 2 mm | 76% | 0.5 m/s | 3.2 |
| 2007 | 21.3°C | 1.2°C | 11.2°C | 4 mm | 68% | 0.5 m/s | 3.4 |
| 2006 | 20.3°C | 3.2°C | 11.7°C | 9 mm | 74% | 0.5 m/s | 3.2 |
| 2005 | 22.0°C | 3.0°C | 12.5°C | 0 mm | 68% | 0.6 m/s | 3.9 |
| 2004 | 24.3°C | 1.3°C | 12.8°C | 10 mm | 74% | 0.5 m/s | 3.3 |
| 2003 | 22.8°C | 1.6°C | 12.2°C | 2 mm | 71% | 0.5 m/s | 3.3 |
| 2002 | 21.8°C | 2.6°C | 12.2°C | 2 mm | 72% | 0.5 m/s | 3.3 |
| 2001 | 21.7°C | 1.4°C | 11.5°C | 4 mm | 66% | 0.6 m/s | 3.4 |
| 2000 | 20.8°C | 2.0°C | 11.4°C | 2 mm | 63% | 0.6 m/s | 3.6 |
| 1999 | 19.4°C | 1.7°C | 10.6°C | 1 mm | 70% | 0.5 m/s | 3.6 |
| 1998 | 24.2°C | 1.2°C | 12.7°C | 4 mm | 60% | 0.6 m/s | 3.7 |
| 1997 | 20.1°C | 1.0°C | 10.5°C | 17 mm | 74% | 0.5 m/s | 3.1 |
| 1996 | 22.3°C | 1.8°C | 12.1°C | 0 mm | 67% | 0.6 m/s | 3.8 |
| 1995 | 19.3°C | 0.8°C | 10.1°C | 15 mm | 80% | 0.4 m/s | 2.9 |
| 1994 | 23.8°C | 0.4°C | 12.1°C | 0 mm | 66% | 0.6 m/s | 3.5 |
| 1993 | 25.1°C | 2.4°C | 13.8°C | 0 mm | 70% | 0.6 m/s | 3.4 |
| 1992 | 19.5°C | 0.7°C | 10.1°C | 2 mm | 70% | 0.6 m/s | 3.7 |
| 1991 | 26.2°C | 0.7°C | 13.4°C | 30 mm | 72% | 0.5 m/s | 3.3 |
| 1990 | 21.7°C | 2.2°C | 12.0°C | 0 mm | 77% | 0.5 m/s | 3.4 |
| 1989 | 26.1°C | 0.0°C | 13.1°C | 9 mm | 69% | 0.5 m/s | 3.6 |
| 1988 | 24.8°C | 2.5°C | 13.6°C | 6 mm | 76% | 0.5 m/s | 3.5 |
| 1987 | 23.6°C | 2.4°C | 13.0°C | 11 mm | 68% | 0.5 m/s | 3.7 |
| 1986 | 21.9°C | -1.3°C | 10.3°C | 9 mm | 70% | 0.5 m/s | 3.3 |
| 1985 🌧️ | 17.9°C | 0.8°C | 9.4°C | 61 mm | 77% | 0.5 m/s | 3.3 |
| 1984 | 22.5°C | 1.7°C | 12.1°C | 15 mm | 74% | 0.5 m/s | 3.2 |
| 1983 | 20.9°C | 0.9°C | 10.9°C | 22 mm | 74% | 0.5 m/s | — |
| 1982 ❄️ | 16.5°C | 0.8°C | 8.6°C | 7 mm | 77% | 0.4 m/s | — |
| 1981 | 19.4°C | 1.6°C | 10.5°C | 20 mm | 78% | 0.5 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 21.5°C with lows near 1.7°C (mean 11.6°C), based on 45 years of NASA POWER data.
December averages 9 mm of rainfall in Upper Siang, one of the drier months. The wettest on record was 61 mm in 1985.
The hottest December reached 26.4°C in 2016. The coldest dipped to -1.3°C in 1986.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 0.9°C. Daytime highs moved from 19.4°C to 20.2°C and overnight lows from 1.2°C to 2.3°C over the same span.
December is one of the cooler months of the year in Upper Siang and one of the drier months, so plan for around 21.5°C daytime highs and 1.7°C at night.
Not quite — December is the 3rd coolest month in Upper Siang, averaging 11.6°C.
For December in Upper Siang, pack warm layers and a jacket for chilly mornings, with typical highs of 21.5°C and lows of 1.7°C.
Relative humidity in December averages 74% — moderately humid.
Average wind speed in December is 0.5 m/s. The windiest December on record averaged 0.6 m/s (1992).
The wettest December on record was 1985 with 61 mm. On average, December sees 9 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 Upper Siang 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.
