Climate averages 1991–2020
Ulan Bator weather
in September.
A mild, fairly dry month: the 5th warmest and the 9th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a mild month in Ulan Bator: daytime highs average 15.6°C and nights cool to about 3.0°C. By daytime temperature it is the 5th warmest of the 12 months.
Expect about 39 mm of rain on roughly 7 days, which makes September a fairly dry month (the 9th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 38 min on an average September day.
The nearest other city in this atlas is Darhan (189 km away). In September its highs average 17.9°C, 2.3°C warmer than Ulan Bator, with 39 mm of rain.
Among the 3 cities listed in Mongolia, Ulan Bator ranks 2nd of 3 for the warmest September highs and joint 2nd of 3 for the driest September (rainfall, lowest first). The mean September high of those 3 cities is 16.1°C; Ulan Bator is 0.5°C cooler than that mean.
From September to October, average highs fall by 9.1°C to 6.5°C, and monthly rainfall falls from 39 mm to 15 mm.
The annual picture
September in context
Monthly precipitation
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
Ulan Bator climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -12.4°C-24.8°C | -24.8°C | 1.5 | 0.5 | 8.99 h |
| February | -7.4°C-21.2°C | -21.2°C | 2.8 | 1.2 | 10.210 h |
| March | 0.9°C-11.9°C | -11.9°C | 7.3 | 2.2 | 11.912 h |
| April | 8.8°C-3.6°C | -3.6°C | 16 | 4.3 | 13.614 h |
| May | 15.8°C1.7°C | 1.7°C | 34 | 6.7 | 15.115 h |
| June | 21.4°C8.4°C | 8.4°C | 55 | 9.5 | 16.016 h |
| July | 23.7°C11.9°C | 11.9°C | 66 | 11.2 | 15.616 h |
| August | 21.7°C9.8°C | 9.8°C | 68 | 10.7 | 14.314 h |
| September, selected | 15.6°C3.0°C | 3.0°C | 39 | 7.2 | 12.613 h |
| October | 6.5°C-4.1°C | -4.1°C | 15 | 3.8 | 10.911 h |
| November | -3.7°C-13.5°C | -13.5°C | 6.1 | 2.1 | 9.39 h |
| December | -10.8°C-20.9°C | -20.9°C | 2.1 | 0.9 | 8.58 h |
Precipitation (rain or snow, as water) is the average of the 30 separate monthly totals. A wet 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
September in nearby cities
- Darhan in SeptemberMongolia · 189 kmHigh 17.9°C · Low 6.2°C · 39 mm rain
- Erdenet in SeptemberMongolia · 241 kmHigh 14.8°C · Low 4.4°C · 38 mm rain
- Ulan-Ude in SeptemberRussia · 439 kmHigh 15.6°C · Low 5.2°C · 44 mm rain
- Irkutsk in SeptemberRussia · 522 kmHigh 15.4°C · Low 5.8°C · 61 mm rain
- Angarsk in SeptemberRussia · 559 kmHigh 15.5°C · Low 5.5°C · 51 mm rain
- Usol’ye-Sibirskoye in SeptemberRussia · 585 kmHigh 15.3°C · Low 5.5°C · 53 mm rain
- Chita in SeptemberRussia · 659 kmHigh 14.7°C · Low 3.9°C · 47 mm rain
- Bayan Nur in SeptemberChina · 798 kmHigh 24.0°C · Low 11.0°C · 32 mm rain
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 limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Ulan Bator) is explained once on the Ulan Bator year overview and on the Sources, method and limits page.