Climate averages 1991–2020
Siwān weather
by month.
See how the year changes. May has the highest average daily maximum; November has the lowest average monthly rainfall.
Pleasant-weather months by our simple rule: JanuaryFebruaryNovemberDecember
Long-term climate patterns, not a forecast for a particular trip.
Across the year Siwān averages a daytime high of 30.5°C and a nighttime low of 20.4°C, with about 1,141 mm of rain on roughly 108 days. May is the warmest month (average high 37.6°C) and January the coolest (21.8°C). July is the wettest month with 329 mm; November is the driest with 4.5 mm.
Months with pleasant weather by a simple rule (average high between 18°C and 29°C, average low of at least 5°C and at most 8 rain days): January, February, November and December. This looks at temperature and rain only, not humidity, wind, sea temperature or crowds.
The annual picture
A year in Siwān
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Siwān climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 21.8°C10.3°C | 10.3°C | 16 | 2.2 | 10.711 h |
| February | 25.7°C13.2°C | 13.2°C | 17 | 2.4 | 11.311 h |
| March | 32.0°C18.2°C | 18.2°C | 12 | 2.1 | 12.012 h |
| April | 37.1°C23.3°C | 23.3°C | 10 | 2.5 | 12.813 h |
| May | 37.6°C26.1°C | 26.1°C | 29 | 5.2 | 13.413 h |
| June | 35.6°C27.0°C | 27.0°C | 180 | 15.5 | 13.814 h |
| July | 31.9°C26.3°C | 26.3°C | 329 | 26.0 | 13.614 h |
| August | 31.5°C26.0°C | 26.0°C | 294 | 26.6 | 13.113 h |
| September | 30.9°C25.0°C | 25.0°C | 205 | 20.5 | 12.312 h |
| October | 30.2°C21.3°C | 21.3°C | 37 | 4.3 | 11.612 h |
| November | 27.8°C16.0°C | 16.0°C | 4.5 | 0.4 | 10.911 h |
| December | 23.7°C11.8°C | 11.8°C | 7.6 | 0.7 | 10.511 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
Nearby cities
- ChāpraIndia · 63 kmHigh 30.6°C · Low 20.8°C · 1,096 mm rain a year
- DeoriaIndia · 65 kmHigh 30.4°C · Low 20.2°C · 1,221 mm rain a year
- BettiahIndia · 66 kmHigh 30.1°C · Low 20.1°C · 1,350 mm rain a year
- MothīhāriIndia · 73 kmHigh 30.3°C · Low 20.3°C · 1,639 mm rain a year
- KushinagarIndia · 74 kmHigh 30.3°C · Low 20.1°C · 1,259 mm rain a year
- ArrahIndia · 80 kmHigh 30.7°C · Low 20.7°C · 1,116 mm rain a year
- BuxarIndia · 81 kmHigh 30.9°C · Low 20.5°C · 1,135 mm rain a year
- MauIndia · 85 kmHigh 30.7°C · Low 20.3°C · 1,147 mm rain a year
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsWhat do the high and low temperatures mean?
We average the daily maximum and daily minimum for each calendar month over 1991–2020. They are not record extremes, a forecast range or temperatures at a fixed time of day.
How is a rain day counted?
A local calendar day (standard time, UTC+5:30, no daylight saving) with at least 1 mm of total precipitation counts as one rain day. We count these for each year and month, then average across 30 years. The average does not predict which days will be wet.
Where do the numbers come from?
ERA5-Land (temperature) and ERA5 (precipitation) reanalysis from the Copernicus Climate Change Service, read from the Open-Meteo open-data archive. Temperature comes from the 0.1° model cell at 26.20°, 84.40° (5 km from the city centre). Rain comes from the 0.25° cell at 26.25°, 84.25°. These are model estimates, not weather-station readings; coast, hills and city streets can differ.
Does this page show sunshine, humidity or sea temperature?
No. The data used here contain air temperature and precipitation only. Daylight hours are calculated from the city's latitude (sunrise to sunset), not measured sunshine.