September is one of the warmer months of the year in Upper Siang, with average highs near 29.1°C and lows around 13.8°C (mean 21.5°C). It is a relatively wet time of year, averaging 314 mm of rainfall and 84% relative humidity across the period.
September is one of the warmer months of the year in Upper Siang. Across 45 years of records, the warmest September in Upper Siang was 1988 — when the month averaged 24.9°C — while the coldest was 1987 at 19.6°C. Typical September days reach 29.1°C with nights near 13.8°C. The long-term trend is warming, about 0.4°C per decade.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 20.9°C | 21.2°C | 21.4°C | 21.5°C | 22.6°C | +1.7°C |
| Avg High | 28.9°C | 29.1°C | 29.6°C | 28.8°C | 29.4°C | +0.5°C |
| Avg Low | 13.0°C | 13.4°C | 13.2°C | 14.3°C | 15.7°C | +2.7°C |
| Avg Rain | 319 mm | 321 mm | 236 mm | 393 mm | 297 mm | -22 mm |
September temperatures in Upper Siang have risen by about 1.8°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 11.1°C (1997) to a record high of 35.4°C (1988).
Rainfall in September is a relatively wet time of year, averaging 314 mm, with a wettest year of 620 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.1°C per decade while lows rose 0.6°C per decade, narrowing the gap between day and night.
One of the best times to visit Upper Siang
September is one of the best times to visit Upper Siang. Expect days averaging 29.1°C and nights around 13.8°C (mean 21.5°C) — warmer than Upper Siang's yearly average — with higher rainfall (314 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | High | Low | Avg | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|
| 2025 | 29.6°C | 17.1°C | 23.3°C | 209 mm | 84% | 0.2 m/s | 4.3 |
| 2024 | 31.6°C | 16.6°C | 24.1°C | 239 mm | 79% | 0.3 m/s | 4.6 |
| 2023 | 30.2°C | 14.7°C | 22.5°C | 123 mm | 79% | 0.2 m/s | 4.5 |
| 2022 | 27.9°C | 14.2°C | 21.1°C | 435 mm | 87% | 0.2 m/s | 3.4 |
| 2021 | 28.4°C | 14.9°C | 21.6°C | 153 mm | 81% | 0.3 m/s | 4.6 |
| 2020 🌧️ | 28.9°C | 16.9°C | 22.9°C | 620 mm | 89% | 0.1 m/s | 3 |
| 2019 | 29.6°C | 13.1°C | 21.3°C | 412 mm | 87% | 0.2 m/s | 3.4 |
| 2018 | 29.5°C | 15.0°C | 22.2°C | 438 mm | 87% | 0.2 m/s | 3.4 |
| 2017 | 29.7°C | 16.8°C | 23.2°C | 328 mm | 87% | 0.2 m/s | 3.5 |
| 2016 | 27.7°C | 15.7°C | 21.7°C | 556 mm | 87% | 0.2 m/s | 3.2 |
| 2015 | 27.4°C | 14.6°C | 21.0°C | 320 mm | 87% | 0.2 m/s | 3.5 |
| 2014 | 28.9°C | 13.7°C | 21.3°C | 313 mm | 84% | 0.2 m/s | 4 |
| 2013 | 28.3°C | 14.1°C | 21.2°C | 288 mm | 84% | 0.2 m/s | 4.1 |
| 2012 | 28.7°C | 15.3°C | 22.0°C | 487 mm | 87% | 0.2 m/s | 3.5 |
| 2011 | 29.5°C | 12.7°C | 21.1°C | 318 mm | 82% | 0.2 m/s | 4.1 |
| 2010 | 28.2°C | 12.4°C | 20.3°C | 471 mm | 84% | 0.2 m/s | 3.5 |
| 2009 | 28.5°C | 13.2°C | 20.9°C | 175 mm | 79% | 0.3 m/s | 4.8 |
| 2008 | 29.3°C | 13.5°C | 21.4°C | 203 mm | 80% | 0.3 m/s | 4.2 |
| 2007 | 30.0°C | 11.5°C | 20.8°C | 349 mm | 80% | 0.3 m/s | 4.1 |
| 2006 | 33.2°C | 13.9°C | 23.5°C | 257 mm | 81% | 0.2 m/s | 3.7 |
| 2005 | 29.3°C | 13.3°C | 21.3°C | 123 mm | 77% | 0.3 m/s | 4.5 |
| 2004 | 29.2°C | 14.3°C | 21.7°C | 189 mm | 82% | 0.3 m/s | 3.9 |
| 2003 | 27.8°C | 14.2°C | 21.0°C | 324 mm | 84% | 0.2 m/s | 3.3 |
| 2002 | 29.1°C | 12.3°C | 20.7°C | 212 mm | 81% | 0.2 m/s | 3.8 |
| 2001 | 29.5°C | 14.5°C | 22.0°C | 231 mm | 82% | 0.3 m/s | 3.6 |
| 2000 | 29.6°C | 11.6°C | 20.6°C | 296 mm | 84% | 0.2 m/s | 3.5 |
| 1999 | 30.4°C | 15.0°C | 22.7°C | 212 mm | 79% | 0.3 m/s | 4.3 |
| 1998 | 29.4°C | 13.4°C | 21.4°C | 172 mm | 79% | 0.3 m/s | 4.5 |
| 1997 | 28.4°C | 11.1°C | 19.8°C | 312 mm | 84% | 0.2 m/s | 3.6 |
| 1996 | 29.0°C | 14.8°C | 21.9°C | 152 mm | 82% | 0.3 m/s | 3.6 |
| 1995 | 30.8°C | 14.1°C | 22.4°C | 434 mm | 84% | 0.2 m/s | 4 |
| 1994 | 29.1°C | 12.6°C | 20.8°C | 286 mm | 80% | 0.3 m/s | 4 |
| 1993 | 27.9°C | 13.9°C | 20.9°C | 453 mm | 84% | 0.2 m/s | 3.3 |
| 1992 | 29.8°C | 11.7°C | 20.7°C | 270 mm | 81% | 0.3 m/s | 3.6 |
| 1991 | 26.5°C | 14.7°C | 20.6°C | 371 mm | 86% | 0.2 m/s | 3.1 |
| 1990 | 29.4°C | 12.8°C | 21.1°C | 548 mm | 85% | 0.2 m/s | 2.9 |
| 1989 | 27.7°C | 13.6°C | 20.6°C | 348 mm | 87% | 0.2 m/s | 3.6 |
| 1988 🔥 | 35.4°C | 14.4°C | 24.9°C | 313 mm | 86% | 0.2 m/s | 2.5 |
| 1987 ❄️ | 26.2°C | 12.9°C | 19.6°C | 438 mm | 88% | 0.2 m/s | 2.6 |
| 1986 | 27.3°C | 12.1°C | 19.7°C | 403 mm | 85% | 0.2 m/s | 3 |
| 1985 | 29.2°C | 12.9°C | 21.0°C | 315 mm | 87% | 0.2 m/s | 3.4 |
| 1984 | 27.7°C | 11.9°C | 19.8°C | 325 mm | 85% | 0.2 m/s | 3.2 |
| 1983 | 28.2°C | 12.4°C | 20.3°C | 278 mm | 86% | 0.2 m/s | — |
| 1982 | 30.2°C | 13.2°C | 21.7°C | 242 mm | 84% | 0.2 m/s | — |
| 1981 | 28.0°C | 13.8°C | 20.9°C | 207 mm | 84% | 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 13.8°C (mean 21.5°C), based on 45 years of NASA POWER data.
September averages 314 mm of rainfall in Upper Siang, a relatively wet time of year. The wettest on record was 620 mm in 2020.
The hottest September reached 35.4°C in 1988. The coldest dipped to 11.1°C in 1997.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.8°C. Daytime highs moved from 28.7°C to 29.5°C and overnight lows from 12.8°C to 15.5°C over the same span.
September is one of the warmer months of the year in Upper Siang and a relatively wet time of year, so plan for around 29.1°C daytime highs and 13.8°C at night.
Not quite — September is the 9th coolest month in Upper Siang, averaging 21.5°C.
For September in Upper Siang, pack light layers you can adjust through the day, with typical highs of 29.1°C and lows of 13.8°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 84% — quite humid.
Average wind speed in September is 0.2 m/s. The windiest September on record averaged 0.3 m/s (1992).
The wettest September on record was 2020 with 620 mm. On average, September sees 314 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 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.
