January is one of the cooler months of the year in Siwan, with average highs near 28.2°C and lows around 4.9°C (mean 16.6°C). It is one of the drier months, averaging 10 mm of rainfall and 48% relative humidity across the period.
January is one of the cooler months of the year in Siwan. Across 45 years of records, the warmest January in Siwan was 1990 — when the month averaged 19.8°C — while the coldest was 2013 at 14.1°C. Typical January days reach 28.2°C with nights near 4.9°C. The long-term trend is cooling, about 0.3°C per decade.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 16.7°C | 17.3°C | 16.5°C | 15.9°C | 16.4°C | -0.3°C |
| Avg High | 28.1°C | 29.5°C | 28.0°C | 27.6°C | 28.0°C | -0.1°C |
| Avg Low | 5.3°C | 5.1°C | 5.0°C | 4.3°C | 4.9°C | -0.4°C |
| Avg Rain | 13 mm | 10 mm | 12 mm | 9 mm | 4 mm | -9 mm |
January temperatures in Siwan have fallen by about 0.7°C between 1981–1985 and 2021–2025.
January has ranged from a record low of 1.3°C (2013) to a record high of 33.5°C (1990).
Rainfall in January is one of the drier months, averaging 10 mm, with a wettest year of 36 mm.
A good time to visit Siwan
January is a good time to visit Siwan, with days averaging 28.2°C and nights around 4.9°C (mean 16.6°C, cooler than Siwan's yearly average) and low rainfall. November and February are marginally more temperate, but January still suits most travellers.
| Year | High | Low | Avg | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|
| 2025 | 30.2°C | 7.0°C | 18.6°C | 0 mm | 47% | 1.7 m/s | 2.3 |
| 2024 | 25.9°C | 6.1°C | 16.0°C | 1 mm | 51% | 1.5 m/s | 1.8 |
| 2023 | 30.3°C | 3.3°C | 16.8°C | 1 mm | 55% | 1.7 m/s | 2.3 |
| 2022 | 24.8°C | 4.3°C | 14.5°C | 14 mm | 76% | 1.8 m/s | 2.3 |
| 2021 | 30.4°C | 4.6°C | 17.5°C | 0 mm | 49% | 1.7 m/s | 2.3 |
| 2020 | 26.1°C | 3.8°C | 15.0°C | 10 mm | 71% | 1.7 m/s | 2.4 |
| 2019 | 29.1°C | 5.9°C | 17.5°C | 7 mm | 43% | 1.6 m/s | 3.1 |
| 2018 | 27.9°C | 4.8°C | 16.4°C | 0 mm | 38% | 1.7 m/s | 2.3 |
| 2017 | 29.9°C | 3.1°C | 16.5°C | 3 mm | 50% | 1.8 m/s | 3.2 |
| 2016 | 30.3°C | 4.8°C | 17.5°C | 8 mm | 34% | 1.5 m/s | 2.8 |
| 2015 | 25.8°C | 4.2°C | 15.0°C | 26 mm | 60% | 1.9 m/s | 2.3 |
| 2014 | 25.4°C | 4.8°C | 15.1°C | 20 mm | 61% | 1.7 m/s | 2.4 |
| 2013 ❄️ | 26.9°C | 1.3°C | 14.1°C | 9 mm | 50% | 1.6 m/s | 3 |
| 2012 | 26.0°C | 4.1°C | 15.1°C | 16 mm | 59% | 1.8 m/s | 3 |
| 2011 | 26.8°C | 3.8°C | 15.3°C | 2 mm | 51% | 1.7 m/s | 3 |
| 2010 | 27.5°C | 5.8°C | 16.6°C | 1 mm | 48% | 1.6 m/s | 2.3 |
| 2009 | 28.4°C | 6.3°C | 17.3°C | 1 mm | 62% | 1.4 m/s | 3 |
| 2008 | 25.8°C | 4.5°C | 15.2°C | 34 mm | 60% | 1.4 m/s | 3.3 |
| 2007 | 28.3°C | 3.8°C | 16.1°C | 0 mm | 39% | 1.5 m/s | 3.4 |
| 2006 | 29.6°C | 5.2°C | 17.4°C | 0 mm | 42% | 1.7 m/s | 3.4 |
| 2005 | 28.1°C | 7.2°C | 17.6°C | 27 mm | 50% | 1.5 m/s | 3.1 |
| 2004 | 26.4°C | 5.6°C | 16.0°C | 27 mm | 51% | 1.3 m/s | 2.4 |
| 2003 | 26.6°C | 3.7°C | 15.2°C | 6 mm | 45% | 1.6 m/s | 2.4 |
| 2002 | 26.6°C | 5.2°C | 15.9°C | 12 mm | 54% | 1.5 m/s | 3.1 |
| 2001 | 30.5°C | 4.1°C | 17.3°C | 6 mm | 39% | 1.6 m/s | 3.4 |
| 2000 | 29.6°C | 4.7°C | 17.1°C | 1 mm | 30% | 1.6 m/s | 3.3 |
| 1999 | 29.6°C | 6.3°C | 18.0°C | 1 mm | 47% | 1.5 m/s | 3.4 |
| 1998 | 26.7°C | 3.9°C | 15.3°C | 2 mm | 50% | 1.6 m/s | 3.1 |
| 1997 | 27.2°C | 4.7°C | 16.0°C | 10 mm | 40% | 1.7 m/s | 4 |
| 1996 | 26.9°C | 3.9°C | 15.4°C | 33 mm | 52% | 1.7 m/s | 3.9 |
| 1995 | 27.7°C | 4.5°C | 16.1°C | 16 mm | 41% | 1.8 m/s | 3.7 |
| 1994 | 31.1°C | 6.9°C | 19.0°C | 21 mm | 44% | 1.7 m/s | 3.8 |
| 1993 | 29.8°C | 4.7°C | 17.2°C | 5 mm | 34% | 2.2 m/s | 3.9 |
| 1992 | 31.0°C | 5.1°C | 18.0°C | 0 mm | 39% | 1.4 m/s | 4.2 |
| 1991 | 31.0°C | 4.8°C | 17.9°C | 8 mm | 40% | 1.5 m/s | 4.4 |
| 1990 🔥 | 33.5°C | 6.2°C | 19.8°C | 0 mm | 30% | 1.8 m/s | 4.1 |
| 1989 | 27.6°C | 3.5°C | 15.6°C | 8 mm | 42% | 1.7 m/s | 4.3 |
| 1988 | 27.9°C | 5.3°C | 16.6°C | 3 mm | 48% | 1.4 m/s | 4.2 |
| 1987 | 28.3°C | 4.6°C | 16.5°C | 6 mm | 42% | 1.4 m/s | 3.7 |
| 1986 | 27.0°C | 2.6°C | 14.8°C | 3 mm | 62% | 1.5 m/s | 3.9 |
| 1985 | 28.3°C | 6.2°C | 17.2°C | 21 mm | 47% | 1.5 m/s | 3.8 |
| 1984 | 29.3°C | 5.9°C | 17.6°C | 8 mm | 40% | 1.8 m/s | 4 |
| 1983 | 28.2°C | 7.2°C | 17.7°C | 1 mm | 34% | 1.4 m/s | — |
| 1982 🌧️ | 29.4°C | 5.7°C | 17.6°C | 36 mm | 53% | 1.7 m/s | — |
| 1981 | 26.5°C | 6.9°C | 16.7°C | 34 mm | 57% | 1.5 m/s | — |
Actual recorded January data for each year, 1981–2025 — sourced from NASA POWER.
The average high in January is around 28.2°C with lows near 4.9°C (mean 16.6°C), based on 45 years of NASA POWER data.
January averages 10 mm of rainfall in Siwan, one of the drier months. The wettest on record was 36 mm in 1982.
The hottest January reached 33.5°C in 1990. The coldest dipped to 1.3°C in 2013.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average January temperatures have fallen by about 0.7°C. Daytime highs moved from 28.3°C to 28.3°C and overnight lows from 6.4°C to 5.1°C over the same span.
January is one of the cooler months of the year in Siwan and one of the drier months, so plan for around 28.2°C daytime highs and 4.9°C at night.
Yes — January is the coldest month of the year in Siwan, averaging 16.6°C.
For January in Siwan, pack warm layers and a jacket for chilly mornings, with typical highs of 28.2°C and lows of 4.9°C.
Relative humidity in January averages 48% — relatively dry.
Average wind speed in January is 1.6 m/s. The windiest January on record averaged 2.2 m/s (1993).
The wettest January on record was 1982 with 36 mm. On average, January sees 10 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 Siwan 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.
