Ulan Bator weather in September
In September, Ulan Bator has daytime highs averaging 16 °C, nights around 2.9 °C, with 7.5 wet days. Figures are 1991–2020 climate normals.
- 15.5°C Average high
- 2.9°C Average low
- 7.5days Wet days
- 39mm Rainfall
- 13h Daylight
Daily temperatures through September
How September develops
Averages for the first, middle and last part of the month, from daily 1991–2020 normals. Chance of rain is the share of years in which that calendar day recorded more than 1 mm.
| Days | Avg high | Avg low | Chance of rain |
|---|---|---|---|
| 1–10 September | 17.9 °C | 5.5 °C | 28 % |
| 11–20 September | 15.6 °C | 2.8 °C | 22 % |
| 21–30 September | 13.3 °C | 0.5 °C | 25 % |
- Average highs fall from 17.9 °C early in September to 13.3 °C by the end of it.
- Rain is most likely over days 1–10 of September (28 % of days) and least likely over days 11–20 (22 %).
What to expect
| Measure | Typical September | Share of the month |
|---|---|---|
| Days above 25 °C | 1.0 of 30 | 3 % |
| Days above 30 °C | 0 of 30 | 0 % |
| Days below 0 °C | 6.8 of 30 | 23 % |
| Days with more than 1 mm rain | 7.5 of 30 | 25 % |
Conditions in September
| Measure | Average |
|---|---|
| Mean temperature | 9.3 °C |
| Record high (1991–2020) | 29 °C |
| Record low (1991–2020) | -8.1 °C |
| Relative humidity | 62 % |
| Wind speed | 16 km/h |
| Cloud cover | 47 % |
Where Ulan Bator ranks in September
| Ranking | Position | Value |
|---|---|---|
| The coolest places in Asia in September | 2ndof 50 | 16 °C |
September compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| July | 23.7 °C | 69 mm | 59 % |
| August | 21.6 °C | 69 mm | 56 % |
| September | 15.5 °C | 39 mm | 47 % |
| October | 6.4 °C | 15 mm | 39 % |
| November | -3.8 °C | 6 mm | 42 % |
See all twelve months for Ulan Bator
- September is the 5th warmest month here.
- It is the 9th driest month of the year.
- It ranks 7th for least cloud cover.
- Days last about 13 hours from sunrise to sunset.
- It rains on 7.5 of 30 days — 25 % of the month.
- Nights are about 13 °C cooler than the middle of the day.
- The hottest September day on record since 1991 reached 29 °C, 13 °C above the usual daytime high.
Nearby destinations in September
| Destination | Avg high | Wet days |
|---|---|---|
| Ulan Bator | 16 °C | 7.5 |
| Ulan-Ude | 16 °C | 8 |
QuestionsSeptember in Ulan Bator, answered
How warm is Ulan Bator in September?
Daily highs average 16 °C and nights fall to about 2.9 °C, a spread of 13 °C between afternoon and dawn. That makes September the 5th warmest month of the year here.
Does it rain much in Ulan Bator in September?
September averages 39 mm of rain, spread over about 8 of the 30 days — 25 % of the month. Cloud cover averages 47 % of the sky.
How long are the days in September?
Ulan Bator averages 13 hours between sunrise and sunset in September. Day length is computed from latitude and date, so it is exact rather than modelled — but it says nothing about how much of that time is sunny.
Data sources and method
- ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
- Open-Meteo — Open-Meteo.com. CC BY 4.0
- NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
- GeoNames — GeoNames.org. CC BY 4.0
- Normal period
- 1991–2020
- Dataset version
- era5-1991-2020-scores1.1
- Last processed
Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: daylight hours, beach and comfort scores, monthly rankings, threshold day counts, chance of a wet day by date, ten-day averages within the month. Full formulas are on the methodology page.
Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.