September is one of the warmer months of the year in Upper Siang, with average highs near 25°C and lows around 16.5°C (mean 20.8°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 2024 — when the month averaged 23.1°C — while the coldest was 1984 at 18.9°C. Typical September days reach 25°C with nights near 16.5°C. The long-term trend is warming, about 0.4°C per decade.
September is a relatively wet time of year in Upper Siang, averaging 314 mm of rainfall. The wettest September on record was 2020 with 620 mm, while the driest were 2005 and 2023 at 123 mm.
Relative humidity in Upper Siang during September averages 84%. The most humid September was 2020 at 89%, and the least humid was 2005 at 77%.
September receives about 3.7 kWh/m²/day of solar energy in Upper Siang. The sunniest September was 2009 at 4.8 kWh/m²/day, and the cloudiest was 1988 at 2.5.
Average wind speed in Upper Siang during September is 0.2 m/s. The windiest Septembers were 2009, 2021 and 2024, among others at 0.3 m/s, while the calmest was 2020 at 0.1 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 19.9°C | 20.5°C | 20.8°C | 21.0°C | 21.9°C | +2°C |
| Avg High | 23.9°C | 24.9°C | 25.5°C | 24.8°C | 26.1°C | +2.2°C |
| Avg Low | 15.9°C | 16.1°C | 16.1°C | 17.2°C | 17.7°C | +1.8°C |
| Avg Rain | 319 mm | 321 mm | 236 mm | 393 mm | 297 mm | -22 mm |
September temperatures in Upper Siang have risen by about 2.1°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.
One of the best times to visit Upper Siang
September is one of the best times to visit Upper Siang. Expect days averaging 25°C and nights around 16.5°C (mean 20.8°C) — warmer than Upper Siang's yearly average — with higher rainfall (314 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 | 26.2°C | 22.3°C | 18.5°C | 29.6°C | 17.1°C | 209 mm | 84% | 0.2 m/s | 4.3 |
| 2024 🔥 | 27.7°C | 23.1°C | 18.5°C | 31.6°C | 16.6°C | 239 mm | 79% | 0.3 m/s | 4.6 |
| 2023 | 27.0°C | 22.0°C | 16.9°C | 30.2°C | 14.7°C | 123 mm | 79% | 0.2 m/s | 4.5 |
| 2022 | 24.4°C | 20.7°C | 17.0°C | 27.9°C | 14.2°C | 435 mm | 87% | 0.2 m/s | 3.4 |
| 2021 | 26.3°C | 21.7°C | 17.1°C | 28.4°C | 14.9°C | 153 mm | 81% | 0.3 m/s | 4.6 |
| 2020 🌧️ | 24.8°C | 21.3°C | 17.9°C | 28.9°C | 16.9°C | 620 mm | 89% | 0.1 m/s | 3 |
| 2019 | 24.3°C | 20.8°C | 17.3°C | 29.6°C | 13.1°C | 412 mm | 87% | 0.2 m/s | 3.4 |
| 2018 | 24.5°C | 21.1°C | 17.6°C | 29.5°C | 15.0°C | 438 mm | 87% | 0.2 m/s | 3.4 |
| 2017 | 25.0°C | 21.4°C | 17.8°C | 29.7°C | 16.8°C | 328 mm | 87% | 0.2 m/s | 3.5 |
| 2016 | 24.4°C | 20.9°C | 17.3°C | 27.7°C | 15.7°C | 556 mm | 87% | 0.2 m/s | 3.2 |
| 2015 | 24.4°C | 20.8°C | 17.1°C | 27.4°C | 14.6°C | 320 mm | 87% | 0.2 m/s | 3.5 |
| 2014 | 24.9°C | 21.0°C | 17.0°C | 28.9°C | 13.7°C | 313 mm | 84% | 0.2 m/s | 4 |
| 2013 | 25.6°C | 21.3°C | 17.0°C | 28.3°C | 14.1°C | 288 mm | 84% | 0.2 m/s | 4.1 |
| 2012 | 23.9°C | 20.6°C | 17.3°C | 28.7°C | 15.3°C | 487 mm | 87% | 0.2 m/s | 3.5 |
| 2011 | 25.9°C | 21.3°C | 16.7°C | 29.5°C | 12.7°C | 318 mm | 82% | 0.2 m/s | 4.1 |
| 2010 | 24.8°C | 20.6°C | 16.5°C | 28.2°C | 12.4°C | 471 mm | 84% | 0.2 m/s | 3.5 |
| 2009 | 26.5°C | 21.3°C | 16.1°C | 28.5°C | 13.2°C | 175 mm | 79% | 0.3 m/s | 4.8 |
| 2008 | 25.8°C | 20.8°C | 15.8°C | 29.3°C | 13.5°C | 203 mm | 80% | 0.3 m/s | 4.2 |
| 2007 | 25.1°C | 20.4°C | 15.8°C | 30.0°C | 11.5°C | 349 mm | 80% | 0.3 m/s | 4.1 |
| 2006 | 25.6°C | 20.9°C | 16.2°C | 33.2°C | 13.9°C | 257 mm | 81% | 0.2 m/s | 3.7 |
| 2005 | 26.8°C | 21.5°C | 16.2°C | 29.3°C | 13.3°C | 123 mm | 77% | 0.3 m/s | 4.5 |
| 2004 | 25.2°C | 20.8°C | 16.4°C | 29.2°C | 14.3°C | 189 mm | 82% | 0.3 m/s | 3.9 |
| 2003 | 24.7°C | 20.8°C | 16.9°C | 27.8°C | 14.2°C | 324 mm | 84% | 0.2 m/s | 3.3 |
| 2002 | 25.3°C | 20.3°C | 15.4°C | 29.1°C | 12.3°C | 212 mm | 81% | 0.2 m/s | 3.8 |
| 2001 | 25.9°C | 21.3°C | 16.8°C | 29.5°C | 14.5°C | 231 mm | 82% | 0.3 m/s | 3.6 |
| 2000 | 24.2°C | 20.0°C | 15.7°C | 29.6°C | 11.6°C | 296 mm | 84% | 0.2 m/s | 3.5 |
| 1999 | 26.5°C | 21.7°C | 16.9°C | 30.4°C | 15.0°C | 212 mm | 79% | 0.3 m/s | 4.3 |
| 1998 | 26.6°C | 21.5°C | 16.5°C | 29.4°C | 13.4°C | 172 mm | 79% | 0.3 m/s | 4.5 |
| 1997 | 23.7°C | 19.5°C | 15.3°C | 28.4°C | 11.1°C | 312 mm | 84% | 0.2 m/s | 3.6 |
| 1996 | 24.9°C | 20.6°C | 16.2°C | 29.0°C | 14.8°C | 152 mm | 82% | 0.3 m/s | 3.6 |
| 1995 | 24.3°C | 20.2°C | 16.2°C | 30.8°C | 14.1°C | 434 mm | 84% | 0.2 m/s | 4 |
| 1994 | 26.2°C | 21.2°C | 16.2°C | 29.1°C | 12.6°C | 286 mm | 80% | 0.3 m/s | 4 |
| 1993 | 23.8°C | 19.7°C | 15.7°C | 27.9°C | 13.9°C | 453 mm | 84% | 0.2 m/s | 3.3 |
| 1992 | 25.5°C | 20.4°C | 15.3°C | 29.8°C | 11.7°C | 270 mm | 81% | 0.3 m/s | 3.6 |
| 1991 | 24.0°C | 20.2°C | 16.4°C | 26.5°C | 14.7°C | 371 mm | 86% | 0.2 m/s | 3.1 |
| 1990 | 23.9°C | 20.0°C | 16.0°C | 29.4°C | 12.8°C | 548 mm | 85% | 0.2 m/s | 2.9 |
| 1989 | 23.9°C | 20.1°C | 16.3°C | 27.7°C | 13.6°C | 348 mm | 87% | 0.2 m/s | 3.6 |
| 1988 | 24.4°C | 20.4°C | 16.4°C | 35.4°C | 14.4°C | 313 mm | 86% | 0.2 m/s | 2.5 |
| 1987 | 23.3°C | 19.9°C | 16.5°C | 26.2°C | 12.9°C | 438 mm | 88% | 0.2 m/s | 2.6 |
| 1986 | 23.3°C | 19.4°C | 15.4°C | 27.3°C | 12.1°C | 403 mm | 85% | 0.2 m/s | 3 |
| 1985 | 23.8°C | 19.8°C | 15.8°C | 29.2°C | 12.9°C | 315 mm | 87% | 0.2 m/s | 3.4 |
| 1984 ❄️ | 23.0°C | 18.9°C | 14.8°C | 27.7°C | 11.9°C | 325 mm | 85% | 0.2 m/s | 3.2 |
| 1983 | 24.6°C | 20.4°C | 16.1°C | 28.2°C | 12.4°C | 278 mm | 86% | 0.2 m/s | — |
| 1982 | 24.6°C | 20.2°C | 15.9°C | 30.2°C | 13.2°C | 242 mm | 84% | 0.2 m/s | — |
| 1981 | 24.4°C | 20.2°C | 16.0°C | 28.0°C | 13.8°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 25°C with lows near 16.5°C (mean 20.8°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 2.1°C. Daytime highs moved from 24.1°C to 26.3°C and overnight lows from 15.7°C to 17.6°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 25°C daytime highs and 16.5°C at night.
Not quite — September is the 9th coolest month in Upper Siang, averaging 20.8°C.
For September in Upper Siang, pack light layers you can adjust through the day, with typical highs of 25°C and lows of 16.5°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.
