September is one of the warmer months of the year in West Siang, with average highs near 29.1°C and lows around 20.8°C (mean 25°C). It is a relatively wet time of year, averaging 365 mm of rainfall and 82% relative humidity across the period.
September is one of the warmer months of the year in West Siang. Across 45 years of records, the warmest September in West Siang was 2024 — when the month averaged 27.3°C — while the coldest was 1984 at 23.1°C. Typical September days reach 29.1°C with nights near 20.8°C. The long-term trend is warming, about 0.4°C per decade.
September is a relatively wet time of year in West Siang, averaging 365 mm of rainfall. The wettest September on record was 2020 with 673 mm, while the driest was 2005 at 132 mm.
Relative humidity in West Siang during September averages 82%. The most humid September was 2012 at 88%, and the least humid was 2005 at 74%.
September receives about 3.6 kWh/m²/day of solar energy in West Siang. The sunniest September was 1998 at 4.7 kWh/m²/day, and the cloudiest was 1988 at 2.6.
Average wind speed in West Siang during September is 0.2 m/s. The windiest Septembers were 2021, 2023 and 2024, among others at 0.3 m/s, while the calmest were 2020, 2022 and 2025, among others at 0.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 24.2°C | 24.8°C | 25.1°C | 25.0°C | 26.1°C | +1.9°C |
| Avg High | 28.1°C | 29.1°C | 29.6°C | 28.6°C | 30.3°C | +2.2°C |
| Avg Low | 20.2°C | 20.4°C | 20.6°C | 21.4°C | 22.0°C | +1.8°C |
| Avg Rain | 374 mm | 388 mm | 268 mm | 459 mm | 320 mm | -54 mm |
September temperatures in West Siang have risen by about 2.2°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 15.7°C (1997) to a record high of 36.3°C (2024).
Rainfall in September is a relatively wet time of year, averaging 365 mm, with a wettest year of 673 mm.
A quieter season to visit West Siang
If your dates are flexible, the more temperate months of October and November tend to be the most comfortable for visiting West Siang. That said, September — with days averaging 29.1°C and nights around 20.8°C (mean 25°C) and higher rainfall (365 mm) — can still be rewarding for travellers who don't mind the warmth, and often means fewer crowds.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 30.1°C | 26.3°C | 22.5°C | 34.7°C | 20.6°C | 233 mm | 83% | 0.2 m/s | 4 |
| 2024 🔥 | 31.7°C | 27.3°C | 22.9°C | 36.3°C | 20.9°C | 294 mm | 78% | 0.3 m/s | 4.6 |
| 2023 | 31.7°C | 26.7°C | 21.7°C | 35.3°C | 19.8°C | 158 mm | 75% | 0.3 m/s | 4.3 |
| 2022 | 29.1°C | 25.1°C | 21.2°C | 32.3°C | 18.7°C | 422 mm | 85% | 0.2 m/s | 3.1 |
| 2021 | 30.6°C | 26.0°C | 21.4°C | 33.7°C | 20.1°C | 139 mm | 79% | 0.3 m/s | 4.4 |
| 2020 🌧️ | 28.7°C | 25.4°C | 22.0°C | 33.9°C | 20.7°C | 673 mm | 87% | 0.2 m/s | 2.9 |
| 2019 | 28.5°C | 25.0°C | 21.5°C | 34.5°C | 17.7°C | 487 mm | 85% | 0.2 m/s | 3.1 |
| 2018 | 28.3°C | 25.0°C | 21.8°C | 33.5°C | 19.9°C | 494 mm | 86% | 0.2 m/s | 3.3 |
| 2017 | 28.7°C | 25.3°C | 21.9°C | 34.0°C | 20.6°C | 380 mm | 86% | 0.2 m/s | 3.3 |
| 2016 | 28.5°C | 25.0°C | 21.4°C | 32.4°C | 18.8°C | 582 mm | 86% | 0.2 m/s | 2.9 |
| 2015 | 28.3°C | 24.8°C | 21.4°C | 31.9°C | 20.1°C | 310 mm | 86% | 0.3 m/s | 3.3 |
| 2014 | 28.6°C | 25.0°C | 21.3°C | 33.3°C | 18.7°C | 424 mm | 83% | 0.3 m/s | 3.8 |
| 2013 | 29.1°C | 25.2°C | 21.3°C | 32.7°C | 18.9°C | 284 mm | 83% | 0.2 m/s | 3.9 |
| 2012 | 27.5°C | 24.5°C | 21.4°C | 33.2°C | 19.2°C | 617 mm | 88% | 0.2 m/s | 3.8 |
| 2011 | 30.0°C | 25.6°C | 21.3°C | 33.8°C | 17.9°C | 402 mm | 80% | 0.3 m/s | 4 |
| 2010 | 28.9°C | 24.9°C | 20.8°C | 32.1°C | 17.7°C | 614 mm | 83% | 0.2 m/s | 3.3 |
| 2009 | 30.6°C | 25.8°C | 20.9°C | 33.1°C | 18.7°C | 229 mm | 77% | 0.3 m/s | 4.6 |
| 2008 | 29.7°C | 25.1°C | 20.5°C | 32.1°C | 18.3°C | 265 mm | 78% | 0.3 m/s | 4 |
| 2007 | 29.1°C | 24.5°C | 20.0°C | 32.3°C | 16.3°C | 386 mm | 78% | 0.3 m/s | 4.2 |
| 2006 | 29.4°C | 25.0°C | 20.6°C | 34.7°C | 18.3°C | 288 mm | 79% | 0.3 m/s | 3.7 |
| 2005 | 31.5°C | 26.2°C | 20.8°C | 34.3°C | 18.7°C | 132 mm | 74% | 0.2 m/s | 4.5 |
| 2004 | 29.2°C | 24.9°C | 20.6°C | 32.0°C | 18.4°C | 187 mm | 80% | 0.3 m/s | 3.7 |
| 2003 | 29.2°C | 25.2°C | 21.1°C | 32.0°C | 19.4°C | 312 mm | 82% | 0.2 m/s | 3 |
| 2002 | 29.5°C | 24.7°C | 20.0°C | 34.0°C | 17.4°C | 264 mm | 80% | 0.2 m/s | 3.8 |
| 2001 | 29.4°C | 25.3°C | 21.1°C | 31.9°C | 19.9°C | 244 mm | 80% | 0.3 m/s | 3.4 |
| 2000 | 28.5°C | 24.2°C | 20.0°C | 35.0°C | 16.4°C | 371 mm | 82% | 0.2 m/s | 3.7 |
| 1999 | 30.4°C | 25.9°C | 21.3°C | 32.8°C | 19.8°C | 238 mm | 78% | 0.3 m/s | 4.3 |
| 1998 | 30.7°C | 25.7°C | 20.8°C | 34.8°C | 17.5°C | 158 mm | 77% | 0.3 m/s | 4.7 |
| 1997 | 27.5°C | 23.6°C | 19.7°C | 33.4°C | 15.7°C | 315 mm | 83% | 0.2 m/s | 4 |
| 1996 | 29.4°C | 25.0°C | 20.6°C | 34.5°C | 19.2°C | 153 mm | 79% | 0.2 m/s | 3.5 |
| 1995 | 28.5°C | 24.4°C | 20.4°C | 34.6°C | 17.9°C | 574 mm | 82% | 0.2 m/s | 3.9 |
| 1994 | 30.4°C | 25.6°C | 20.7°C | 34.2°C | 16.3°C | 378 mm | 78% | 0.2 m/s | 3.9 |
| 1993 | 28.5°C | 24.3°C | 20.1°C | 32.9°C | 17.8°C | 507 mm | 81% | 0.2 m/s | 3.6 |
| 1992 | 29.2°C | 24.5°C | 19.8°C | 33.6°C | 17.1°C | 380 mm | 79% | 0.3 m/s | 3.2 |
| 1991 | 28.3°C | 24.4°C | 20.6°C | 31.5°C | 18.7°C | 500 mm | 83% | 0.2 m/s | 3 |
| 1990 | 28.1°C | 24.2°C | 20.4°C | 34.9°C | 16.8°C | 672 mm | 84% | 0.2 m/s | 2.9 |
| 1989 | 28.1°C | 24.4°C | 20.6°C | 31.4°C | 18.7°C | 428 mm | 84% | 0.2 m/s | 3.5 |
| 1988 | 28.5°C | 24.6°C | 20.6°C | 31.7°C | 19.3°C | 375 mm | 84% | 0.2 m/s | 2.6 |
| 1987 | 27.9°C | 24.2°C | 20.6°C | 30.7°C | 17.2°C | 499 mm | 85% | 0.2 m/s | 3.1 |
| 1986 | 27.7°C | 23.7°C | 19.7°C | 32.7°C | 16.3°C | 445 mm | 83% | 0.2 m/s | 2.8 |
| 1985 | 27.9°C | 24.0°C | 20.2°C | 34.2°C | 18.3°C | 338 mm | 84% | 0.2 m/s | 3.1 |
| 1984 ❄️ | 27.2°C | 23.1°C | 19.0°C | 31.9°C | 16.1°C | 416 mm | 83% | 0.3 m/s | 3 |
| 1983 | 28.7°C | 24.6°C | 20.5°C | 32.3°C | 17.3°C | 368 mm | 84% | 0.2 m/s | — |
| 1982 | 28.6°C | 24.4°C | 20.2°C | 35.1°C | 18.0°C | 260 mm | 82% | 0.3 m/s | — |
| 1981 | 28.6°C | 24.5°C | 20.4°C | 31.9°C | 18.6°C | 239 mm | 82% | 0.2 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 29.1°C with lows near 20.8°C (mean 25°C), based on 45 years of NASA POWER data.
September averages 365 mm of rainfall in West Siang, a relatively wet time of year. The wettest on record was 673 mm in 2020.
The hottest September reached 36.3°C in 2024. The coldest dipped to 15.7°C in 1997.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 2.2°C. Daytime highs moved from 28.2°C to 30.6°C and overnight lows from 20.1°C to 21.9°C over the same span.
September is one of the warmer months of the year in West Siang and a relatively wet time of year, so plan for around 29.1°C daytime highs and 20.8°C at night.
Not quite — September is the 9th coolest month in West Siang, averaging 25°C.
For September in West Siang, pack light layers you can adjust through the day, with typical highs of 29.1°C and lows of 20.8°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 82% — quite humid.
Average wind speed in September is 0.2 m/s. The windiest September on record averaged 0.3 m/s (1982).
The wettest September on record was 2020 with 673 mm. On average, September sees 365 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 West Siang behaves each September, 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 September specifically, along with year-by-year records and how the month has changed over the decades.
