Last updated: August 28, 2025
September in Ulan Bator, Mongolia presents a striking transition toward autumn, characterized by maximum temperatures reaching 27°C (81°F) and an average of 9°C (48°F). Daily life is influenced by cooler evenings, with temperatures dipping to a brisk minimum of -9°C (16°F). The city's weather during this month also brings 51 mm (2.0 in) of precipitation over approximately 8 days, resulting in a humidity level of 65%. These dynamic conditions create a unique atmosphere, inviting both locals and travelers to experience the changing season in this vibrant capital.
In September, Ulan Bator transitions gracefully from the warmth of summer into the crisp embrace of autumn. The average temperature hovers around 9°C (48°F), reflecting a notable cool down from the previous months. Nighttime lows dip to -9°C (16°F), as the city prepares for the colder months ahead. However, the daytime still offers a pleasant warmth, with highs reaching up to 27°C (81°F), making it an ideal time for outdoor exploration. As the days become shorter and the air turns crisp, September serves as a gentle reminder of the approaching winter, while still allowing residents and visitors to enjoy the last vestiges of warmth before the chill sets in.
September marks a notable transition in Ulan Bator's precipitation patterns, with 51 mm (2.0 in) of rain falling over an average of 8 days. This amount represents a significant drop from August’s peak of 83 mm (3.3 in), yet it remains the second-highest monthly total of the latter half of the year. As summer wanes, the frequency of rainfall continues to reflect a diminishing trend, with October typically bringing even lower totals. Despite this decrease, September’s rainfall serves as a crucial buffer, nourishing the landscape as it shifts into the cooler autumn months ahead. The shift from the rainy peak of midsummer to the moderate autumn precipitation sets the stage for Ulan Bator's climatic transition, highlighting the region's extremes.
As autumn approaches in Ulan Bator, September's humidity levels rise to 65%, a slight increase from the milder summer months where humidity hovered around 57% to 58%. This transitional month marks a shift from the drier conditions of May and June, which recorded their lowest levels of about 50%. Notably, September's humidity is on par with October's, suggesting a trend of relatively stable moisture levels as the city prepares for the colder months ahead. As winter looms, humidity will climb further to 67% in November and 89% by December, highlighting a persistent increase as the year draws to a close. With these shifts, September serves as a pivotal moment in Ulan Bator's climatic rhythm, bridging the dry warmth of summer with the icy grip of winter.
In September, Ulan Bator experiences a notable shift in its UV Index, registering at 6—a decrease from the summer months but still categorized as high. This means that while the harsh summer sun begins to wane, outdoor enthusiasts should remain vigilant, with a burn time of 25 minutes before sun protection becomes essential. The trend from early in the year shows a gradual rise in UV exposure, peaking at a very high level during the summer months of May through August, where the UV Index consistently stayed at 9. As autumn approaches in October, the UV Index drops further, indicating a transition to more moderate sun exposure. For more detailed information, check out the Ulan Bator UV Index.
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As the calendars turn to September, Ulan Bator basks in a remarkable 311 hours of sunshine, continuing its pattern of brightening days. Following the summer months, which peak with July's 373 hours, September's warmth signals a graceful transition into autumn. Despite a subtle decline from August's 346 hours, the sunlight remains abundant, reflecting the city's vibrant energy as it prepares for the cooler months ahead. With the daylight hours gradually waning, September offers a beautiful blend of lingering summer warmth and the crisp promise of fall, making it a captivating time to experience Ulan Bator's dynamic landscape.
In Ulan Bator, September marks a noteworthy transition in the weather patterns as the chance of sunny days rises to 51%. This slight increase in sunshine compared to the summer months, where the chances linger around 41%, suggests a welcomed shift as the region gears up for autumn. Although still lower than the clearer skies of October, which boasts a 69% chance of sun, September offers a refreshing balance of lingering warmth and the crispness of the fall season. As daylight begins to wane, this month serves as a beautiful bridge between the sun-drenched days of summer and the brighter, clearer skies that follow.
In Ulan Bator, Mongolia, the daylight duration showcases a clear seasonal rhythm as the year progresses. September marks a gentle transition, with 12 hours of daylight, a decrease from the peak of 15 hours seen during the summer months of June and July. As autumn approaches, the city starts to experience shorter days, following a gradual decline that began in August. This ongoing shift reminds residents of the impending winter, as daylight will continue to wane, reducing to just 8 hours by January. The pattern exhibits a vibrant dance of light, illustrating the unique beauty of Mongolia's changing seasons.
As September arrives in Ulan Bator, the city experiences a gentle breeze with an average wind speed of 2.6 m/s (6 mph), mirroring the calmness of its early winter months. This slight uptick from the summer's 2.3 m/s (5 mph) in July suggests a transition, as the winds are noticeable yet not overpowering. The wind speeds show an interesting trend throughout the year, with a modest rise in the spring to a peak of 3.8 m/s (9 mph) in May, before tapering off as the seasons shift. By September, the winds are just enough to carry the crispness of autumn, setting a serene backdrop for the stunning changes in Ulan Bator's landscape. As the year progresses, September's winds hint at the impending chill of winter, creating an atmosphere that is both refreshing and tranquil.
Weather in Ulan Bator varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Ulan Bator, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January present strikingly contrasting weather conditions. In September, temperatures range from a chilly minimum of -9°C (16°F) to a pleasant average of 9°C (48°F), peaking at a warm 27°C (81°F). The month sees some precipitation, totaling 51 mm (2.0 in) over about 8 days, with a moderate humidity level of 65%. In contrast, January's conditions are far more severe, with temperatures plummeting to a frigid minimum of -42°C (-44°F) and an average temperature of -22°C (-8°F), not exceeding a maximum of -5°C (23°F). This month experiences very little precipitation—only 2 mm (0.1 in)—and boasts humidity levels rising to a notable 92%. For more details, visit the link: Ulan Bator weather in January.
In comparing the weather between September and February, significant differences are evident. September typically sees much milder temperatures, with average highs around 27°C (81°F) and lows of -9°C (16°F), making it a transitional month as summer fades. In contrast, February experiences harsh cold, with average temperatures plummeting to -18°C (0°F) and daily highs rarely reaching above freezing, peaking at only 4°C (39°F). Furthermore, September receives more precipitation, averaging 51 mm (2.0 in) over 8 days, while February is notably drier, with just 5 mm (0.2 in) over 1 day. Humidity levels in February are higher at 84%, compared to the more moderate 65% in September, adding to the overall chill of the winter month. For those looking for more detailed information, you can check out the Ulan Bator weather in February.
When comparing the weather in September and March, the differences are stark. September boasts a milder temperature range, with minimums of -9°C (16°F) and maximums reaching up to 27°C (81°F), averaging around 9°C (48°F). In contrast, March experiences much colder conditions, with minimum temperatures plummeting to -29°C (-20°F) and maximums only climbing to 16°C (61°F), resulting in an average of -7°C (20°F). Additionally, precipitation is more common in September, with 51 mm (2.0 in) over 8 days, whereas March sees a mere 7 mm (0.3 in) over just 2 days. Both months have similar humidity levels, hovering around 65% in September and 64% in March. For a closer look at March weather, you can check Ulan Bator weather in March.
Comparing the weather in September and April reveals notable differences in temperature, precipitation, and humidity. In September, temperatures range from a minimum of -9°C (16°F) to a maximum of 27°C (81°F), with an average around 9°C (48°F). The month experiences 51 mm (2.0 in) of precipitation over approximately 8 days, contributing to a humidity level of 65%. In contrast, April has cooler conditions, with temperatures dipping from a minimum of -16°C (4°F) to a maximum of 25°C (77°F), and an average of just 2°C (36°F). The precipitation in April is significantly lower at 15 mm (0.6 in), occurring on about 4 days, with a humidity level of 59%. For a more detailed look at April weather, check out Ulan Bator weather in April.
In comparing the weather between September and May, we see a notable difference in temperature and precipitation patterns. September experiences a wider temperature range, with minimums dipping to -9°C (16°F) and maximums reaching 27°C (81°F), while May has a slightly milder range with minimums at -8°C (18°F) and maximums peaking at 30°C (87°F). Additionally, September sees more rainfall, with an average of 51 mm (2.0 in) over 8 days, compared to May's lighter precipitation of 26 mm (1.0 in) over just 5 days. Humidity levels also vary, as September averages 65%, making it a bit more humid than May, which holds a lower average of 50%. For more detailed information on May weather specifically, you can check Ulan Bator weather in May.
September weather in Ulan Bator exhibits a more varied temperature range compared to June, with minimums dipping to -9°C (16°F) and maximums reaching up to 27°C (81°F). The average temperature in September is 9°C (48°F), while June enjoys warmer conditions with averages around 15°C (59°F) and highs reaching 32°C (90°F). Additionally, September experiences slightly more precipitation at 51 mm (2.0 in) over 8 days, compared to June's 44 mm (1.7 in) over 7 days. Humidity levels also differ, with September being more humid at 65%, compared to June's 55%. For a more detailed look at June conditions, visit Ulan Bator weather in June.
September and July present notable differences in weather patterns. In September, temperatures range from a chilly minimum of -9°C (16°F) to a comfortable maximum of 27°C (81°F), averaging around 9°C (48°F). In contrast, July enjoys warmer temperatures, with a minimum of 5°C (41°F) and a maximum of 32°C (91°F), resulting in an overall average of 17°C (64°F). Precipitation levels also vary, as September experiences 51 mm (2.0 in) over about 8 days, while July sees more rainfall at 72 mm (2.9 in) across 12 days. Additionally, September has a higher humidity level at 65% compared to July's 57%. For more detailed insights, you can check Ulan Bator weather in July.
In comparing the weather of September and August, we observe notable differences in temperature and precipitation patterns. September experiences a broader temperature range, with minimums dropping to -9°C (16°F) and maximums peaking at 27°C (81°F), resulting in an average of 9°C (48°F). In contrast, August maintains milder temperatures, with minimums at 0°C (33°F) and maximums reaching 28°C (82°F), yielding an average of 14°C (58°F). Additionally, September sees less precipitation than August, with 51 mm (2.0 in) of rainfall over 8 days compared to 83 mm (3.3 in) over 13 days in August. The humidity is also slightly higher in September at 65% compared to August's 58%. For more detailed information, you can check Ulan Bator weather in August.
September and October present a stark contrast in weather conditions. In September, temperatures range from a minimum of -9°C (16°F) to a balmy maximum of 27°C (81°F), averaging around 9°C (48°F). The month features around 51 mm (2.0 in) of precipitation over about 8 days, maintaining a humidity level of 65%. In contrast, October sees much colder temperatures with a minimum of -16°C (4°F) and an average temperature dropping to -1°C (30°F), though it can still reach up to 22°C (72°F) at its highest. October produces significantly less precipitation at 21 mm (0.8 in) over just 4 days, yet still holds the same humidity level at 65%. For a more detailed look at conditions, visit Ulan Bator weather in October.
September and November present stark contrasts in weather conditions. In September, temperatures range from a minimum of -9°C (16°F) to a maximum of 27°C (81°F), with an average of 9°C (48°F). The month experiences 51 mm (2.0 in) of precipitation over 8 days, accompanied by a humidity level of 65%. By November, the landscape shifts dramatically as temperatures drop significantly, with a minimum of -35°C (-32°F) and an average of -12°C (11°F), peaking at a mere 9°C (49°F). Precipitation decreases to just 10 mm (0.4 in) over only 2 days, and humidity rises slightly to 67%. For more specific insights on November's conditions, you can visit Ulan Bator weather in November.
In comparing the weather between September and December, it is clear that they differ significantly. September boasts a broader temperature range, with minimums around -9°C (16°F) and maximums reaching 27°C (81°F), resulting in a mild average of 9°C (48°F). This month also experiences moderate precipitation at 51 mm (2.0 in) over about 8 days, coupled with a humidity level of 65%. In stark contrast, December brings harsher winter conditions, with temperatures plummeting to a minimum of -39°C (-38°F) and an average of -21°C (-5°F), while the maximum temperatures barely reach -3°C (28°F). The precipitation decreases significantly to just 3 mm (0.1 in) across the month, with no recorded rainy days, and humidity rises to 89%, creating a crisp, dry cold. For more details on December weather in Ulan Bator, you can visit Ulan Bator weather in December.
September in Ulan Bator marks a notable transition in weather as the city moves from the warmth of summer into the cool embrace of autumn. With average temperatures dipping to a crisp 9°C and occasional peaks reaching 27°C, it's a time when the cool air begins to set in, especially with nighttime lows falling to around -9°C. While rainfall is moderate, with around 51 mm falling over approximately 8 days, humidity levels hover around 65%, lending an invigorating freshness to the air. This month stands out, offering a unique blend of warm days and cool evenings, making it a delightful time for outdoor exploration. For a deeper understanding of what to expect throughout the year, check out the detailed insights on Ulan Bator Climate.