September is one of the warmer months of the year in Sitamarhi, with average highs near 34.2°C and lows around 22.4°C (mean 28.3°C). It is a relatively wet time of year, averaging 183 mm of rainfall and 83% relative humidity across the period.
September is one of the warmer months of the year in Sitamarhi. Across 45 years of records, the warmest September in Sitamarhi was 1983 — when the month averaged 31.1°C — while the coldest was 1984 at 25.7°C. Typical September days reach 34.2°C with nights near 22.4°C. The long-term September temperature trend is broadly flat.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 28.1°C | 28.4°C | 28.2°C | 28.1°C | 28.8°C | +0.7°C |
| Avg High | 34.3°C | 34.8°C | 33.9°C | 34.1°C | 34.0°C | -0.3°C |
| Avg Low | 21.9°C | 22.1°C | 22.5°C | 22.2°C | 23.7°C | +1.8°C |
| Avg Rain | 179 mm | 141 mm | 169 mm | 218 mm | 225 mm | +46 mm |
September temperatures in Sitamarhi have risen by about 0.8°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 18°C (1994) to a record high of 37.8°C (1983).
Rainfall in September is a relatively wet time of year, averaging 183 mm, with a wettest year of 373 mm.
Daytime highs and overnight lows have shifted differently — highs fell about 0.1°C per decade while lows rose 0.3°C per decade, narrowing the gap between day and night.
A good time to visit Sitamarhi
September is a good time to visit Sitamarhi, with days averaging 34.2°C and nights around 22.4°C (mean 28.3°C, warmer than Sitamarhi's yearly average) and higher rainfall. November and February are marginally more temperate, but September still suits most travellers.
| Year | High | Low | Avg | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|
| 2025 | 34.8°C | 24.4°C | 29.6°C | 211 mm | 84% | 1.6 m/s | 4.6 |
| 2024 | 36.3°C | 23.2°C | 29.7°C | 263 mm | 86% | 2.1 m/s | 4.5 |
| 2023 | 33.2°C | 23.9°C | 28.6°C | 214 mm | 88% | 2 m/s | 4.4 |
| 2022 | 33.1°C | 23.5°C | 28.3°C | 187 mm | 86% | 1.8 m/s | 4 |
| 2021 | 32.5°C | 24.1°C | 28.3°C | 122 mm | 89% | 1.9 m/s | 4.8 |
| 2020 | 34.2°C | 22.9°C | 28.5°C | 351 mm | 87% | 1.5 m/s | 4 |
| 2019 | 35.4°C | 21.3°C | 28.3°C | 279 mm | 84% | 2.2 m/s | 4 |
| 2018 | 35.8°C | 24.0°C | 29.9°C | 111 mm | 78% | 2.1 m/s | 4.9 |
| 2017 | 34.1°C | 24.5°C | 29.3°C | 105 mm | 86% | 1.6 m/s | 4.7 |
| 2016 | 33.9°C | 23.2°C | 28.5°C | 330 mm | 87% | 1.4 m/s | 3.9 |
| 2015 | 33.6°C | 19.5°C | 26.6°C | 155 mm | 84% | 1.5 m/s | 4.9 |
| 2014 | 33.1°C | 21.5°C | 27.3°C | 251 mm | 86% | 1.6 m/s | 4.6 |
| 2013 | 34.1°C | 22.7°C | 28.4°C | 246 mm | 83% | 1.6 m/s | 5.1 |
| 2012 | 33.8°C | 21.4°C | 27.6°C | 270 mm | 84% | 1.7 m/s | 4.6 |
| 2011 | 34.5°C | 22.2°C | 28.3°C | 262 mm | 86% | 2.1 m/s | 4.6 |
| 2010 | 32.5°C | 21.9°C | 27.2°C | 173 mm | 86% | 2.1 m/s | 4.7 |
| 2009 | 34.6°C | 23.4°C | 29.0°C | 93 mm | 84% | 1.8 m/s | 5 |
| 2008 | 32.2°C | 22.1°C | 27.1°C | 224 mm | 87% | 1.6 m/s | 5 |
| 2007 | 32.2°C | 22.0°C | 27.1°C | 297 mm | 87% | 1.9 m/s | 4.3 |
| 2006 | 33.6°C | 22.0°C | 27.8°C | 260 mm | 85% | 2 m/s | 4.6 |
| 2005 | 33.8°C | 23.0°C | 28.4°C | 86 mm | 84% | 1.9 m/s | 5 |
| 2004 | 33.4°C | 22.5°C | 27.9°C | 103 mm | 82% | 1.5 m/s | 4.7 |
| 2003 | 36.1°C | 22.8°C | 29.4°C | 116 mm | 78% | 2.4 m/s | 4.7 |
| 2002 | 37.1°C | 23.4°C | 30.2°C | 92 mm | 72% | 2.5 m/s | 4.8 |
| 2001 | 32.9°C | 22.5°C | 27.7°C | 221 mm | 85% | 1.5 m/s | 4.5 |
| 2000 | 33.1°C | 21.6°C | 27.4°C | 195 mm | 85% | 2.4 m/s | 4.4 |
| 1999 | 35.7°C | 23.5°C | 29.6°C | 82 mm | 78% | 2.6 m/s | 4.9 |
| 1998 | 34.3°C | 23.8°C | 29.0°C | 192 mm | 84% | 2 m/s | 5 |
| 1997 | 33.9°C | 21.7°C | 27.8°C | 93 mm | 82% | 1.8 m/s | 4.7 |
| 1996 | 33.5°C | 22.7°C | 28.1°C | 149 mm | 82% | 1.6 m/s | 5.4 |
| 1995 | 34.6°C | 22.0°C | 28.3°C | 137 mm | 82% | 2.4 m/s | 5 |
| 1994 | 36.2°C | 18.0°C | 27.1°C | 159 mm | 76% | 2.2 m/s | 5.4 |
| 1993 | 34.8°C | 22.3°C | 28.6°C | 229 mm | 82% | 2.4 m/s | 4.7 |
| 1992 | 37.0°C | 22.1°C | 29.6°C | 74 mm | 70% | 2.1 m/s | 5 |
| 1991 | 33.6°C | 22.9°C | 28.3°C | 179 mm | 81% | 1.8 m/s | 4.4 |
| 1990 | 33.9°C | 22.2°C | 28.0°C | 119 mm | 84% | 2 m/s | 4.2 |
| 1989 | 36.6°C | 23.1°C | 29.8°C | 122 mm | 76% | 2.3 m/s | 4.3 |
| 1988 | 33.3°C | 21.8°C | 27.6°C | 129 mm | 86% | 1.8 m/s | 4.7 |
| 1987 🌧️ | 32.1°C | 22.0°C | 27.0°C | 373 mm | 88% | 1.7 m/s | 4.5 |
| 1986 | 35.2°C | 21.3°C | 28.3°C | 98 mm | 78% | 2.5 m/s | 5.1 |
| 1985 | 32.8°C | 22.6°C | 27.7°C | 284 mm | 88% | 1.8 m/s | 4.5 |
| 1984 ❄️ | 31.5°C | 19.9°C | 25.7°C | 246 mm | 87% | 1.8 m/s | 4.7 |
| 1983 🔥 | 37.8°C | 24.4°C | 31.1°C | 54 mm | 71% | 2.6 m/s | — |
| 1982 | 35.7°C | 20.1°C | 27.9°C | 140 mm | 80% | 1.8 m/s | — |
| 1981 | 33.5°C | 22.3°C | 27.9°C | 164 mm | 87% | 1.9 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 34.2°C with lows near 22.4°C (mean 28.3°C), based on 45 years of NASA POWER data.
September averages 183 mm of rainfall in Sitamarhi, a relatively wet time of year. The wettest on record was 373 mm in 1987.
The hottest September reached 37.8°C in 1983. The coldest dipped to 18°C in 1994.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 0.8°C. Daytime highs moved from 34.3°C to 34°C and overnight lows from 21.9°C to 23.8°C over the same span.
September is one of the warmer months of the year in Sitamarhi and a relatively wet time of year, so plan for around 34.2°C daytime highs and 22.4°C at night.
Not quite — September is the 7th coolest month in Sitamarhi, averaging 28.3°C.
For September in Sitamarhi, pack light, breathable clothing and sun protection, with typical highs of 34.2°C and lows of 22.4°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 83% — quite humid.
Average wind speed in September is 1.9 m/s. The windiest September on record averaged 2.6 m/s (1983).
The wettest September on record was 1987 with 373 mm. On average, September sees 183 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 Sitamarhi 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.
