Last updated: August 28, 2025
In September, Lang Son, Vietnam experiences a dynamic climate characterized by warm temperatures with a maximum reaching 34°C (94°F) and an average of 26°C (80°F). The nights cool down to a minimum of 19°C (67°F), providing some respite. This month is marked by significant precipitation, totaling 198 mm (7.8 in) over approximately 22 rainy days, leading to a high humidity level of 82%. Visitors should be prepared for both sunny moments and frequent showers, making it a vibrant yet unpredictable time to explore this beautiful region.
In September, Lang Son, Vietnam experiences a subtle transition as temperatures begin to cool slightly from the sweltering summer months. With a minimum of 19°C (67°F), the mornings are refreshingly mild, while the average temperature settles at a comfortable 26°C (80°F), providing a pleasant backdrop for outdoor exploration. The daytime peaks at 34°C (94°F), ensuring that the afternoons still offer ample warmth but not the oppressive heat seen in the preceding months. As the region starts to prepare for the autumn, September represents a sweet spot—a blend of lingering summer warmth and the gentle arrival of fall breezes, making it an ideal time for visitors to enjoy both the vibrant landscapes and local culture.
September in Lang Son, Vietnam, experiences a noteworthy precipitation total of 198 mm (7.8 in), signaling a substantial decline from August's peak of 346 mm (13.6 in). Despite this drop, September remains a month of robust rainfall, with 22 rainy days contributing to the vibrant, lush landscapes characteristic of the region. Interestingly, this pattern follows a trend of increasing precipitation from earlier months, peaking in August, and then gently tapering off into October's expected 170 mm (6.7 in). The overall rainfall pattern reveals a clear seasonal rhythm, with the wettest months pushing the boundaries of typical tropical climates, while September retains a significant amount of moisture, supporting both agriculture and the diverse local ecosystems.
In September, Lang Son, Vietnam, experiences a notable humidity level of 82%, continuing the trend of elevated moisture that peaks in the heart of summer. Following the sweltering months of July and August—when humidity rises to 90% and 89%, respectively—September marks a slight decrease, yet it remains significantly high. This month serves as a transitional period, with humidity levels starting to drop as the region gently shifts towards the drier autumn months. However, compared to earlier in the year, September still reflects the lingering warmth of summer, showcasing a typical pattern of increasing humidity from the beginning of the year, reaching its climax mid-year before gradually tapering off.
As September rolls into Lang Son, Vietnam, the UV Index remains steady at 13, categorizing the exposure as extreme with an equally brisk burn time of just 10 minutes. This trend mirrors the heightened levels seen throughout the summer months, particularly August, which peaked at 14. With consistent extreme readings from April through September, it's crucial for residents and visitors to remain vigilant about sun safety during this time. As we transition into October, there's a slight dip in the index to 11, yet the autumn months still require attention to UV exposure. For detailed information on UV levels year-round, visit Lang Son UV Index.
UV Risk Categories
As summer fades and September rolls in, Lang Son, Vietnam, enjoys a remarkable 285 hours of sunshine, marking a peak in the transitional months. This period showcases a vibrant continuation of the summer's warmth, though slightly less than the sun-drenched heights of May and July. The sunshine hours gradually tapered off from the lush month of August, yet September still offers plenty of bright days, making it an ideal time for outdoor exploration. Transitioning into autumn, the sun begins to set earlier, with October bringing a gentle decline to 252 hours. This trend hints at the encroaching cooler days ahead, yet September stands out as a vibrant bridge from summer to fall, inviting locals and travelers alike to revel in the lingering sunshine.
In Lang Son, Vietnam, September offers a 24% chance of sunny weather, a modest increase compared to the preceding months of August and June, which see their sunlit probabilities dip to 11%. This slight resurgence marks a transition as the region moves towards the cooler months; however, September remains one of the less promising months for sunshine, falling in line with the cool, rainy season that characterizes late summer. As autumn approaches, the likelihood of sun starts to rise again, with October showcasing a 31% chance. So, while September may not boast the brightest skies, it hints at the gradual return of sunnier days just around the corner.
As summer winds down in Lang Son, Vietnam, September marks a transition back to shorter daylight hours, with approximately 12 hours of sunlight each day. This steady length of daylight mirrors the twilight of August and serves as a gentle reminder that the days are beginning to shorten as autumn approaches. Following the peak of 13 hours seen in the vibrant months of May through July, September maintains this moderate brightness, paving the way for October's gradual decline. The progression of daylight throughout the year illustrates a rhythmic pattern, where every month offers a unique balance of sun and shade, inviting residents and visitors to embrace both the lingering warmth of summer and the welcoming coolness of fall.
As September rolls into Lang Son, Vietnam, the gentle caress of the wind begins to soften, with average speeds dropping to a modest 1.5 m/s (3 mph). This marked decrease follows a pattern of gradual decline from the more spirited breezes of late spring, peaking at 3.3 m/s in May. The summer months see a further dip, culminating in this tranquil September air, where the environment shifts towards a serene stillness. However, as the year progresses into October, a revitalizing surge of wind returns, hinting at the seasonal changes ahead. This transition reflects the dance between nature's rhythms, where September serves as a quiet interlude before the breezy embrace of autumn descends upon the region once again.
Weather in Lang Son varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Lang Son, focusing on differences in temperature, rainfall, humidity, and UV levels.
September weather is characterized by warm temperatures, with a minimum of 19°C (67°F) and an average of 26°C (80°F), rising to a maximum of 34°C (94°F). This month also experiences significant rainfall, totaling 198 mm (7.8 in) over 22 days, paired with high humidity at around 82%. In contrast, January presents much cooler conditions, with temperatures ranging from a minimum of 4°C (40°F) to an average of 15°C (59°F) and a maximum of 27°C (80°F). Precipitation during this month is notably reduced, totaling 55 mm (2.2 in) over just 11 days, and humidity drops to 66%. For more detailed information, check out Lang Son weather in January.
In September, the weather tends to be significantly warmer and more humid compared to February. With average temperatures reaching 26°C (80°F) and highs of 34°C (94°F), it is a stark contrast to February's milder temperatures, which range from a minimum of 5°C (41°F) to an average of 16°C (61°F) and a maximum of 28°C (83°F). Additionally, September experiences much higher precipitation, with 198 mm (7.8 in) falling over 22 days, making it one of the wettest months, whereas February sees only 57 mm (2.2 in) of rain over just 11 days. The humidity in September is also notably higher at 82%, compared to February's 71%. This variation in weather highlights the dramatic shift from the height of summer to the cooler winter months. For a detailed overview of February weather, you can visit Lang Son weather in February.
In September, the weather is significantly warmer and more humid, with average temperatures reaching 26°C (80°F) and maximums soaring up to 34°C (94°F). This month also sees substantial rainfall, totaling 198 mm (7.8 in) over 22 days, contributing to a high humidity level of 82%. In contrast, March presents a cooler climate, with average temperatures around 20°C (68°F) and maximums of 32°C (89°F). Precipitation in March is much lower, at 92 mm (3.6 in), and it occurs over 21 days, along with a reduced humidity of 69%. For more detailed insights, check out Lang Son weather in March.
September and April present contrasting weather conditions. In September, temperatures range from a minimum of 19°C (67°F) to a maximum of 34°C (94°F), with an average of 26°C (80°F). This month also experiences significant rainfall, with 198 mm (7.8 inches) of precipitation spread over 22 days, resulting in high humidity levels of 82%. In contrast, April showcases milder temperatures, with a minimum of 10°C (50°F), an average of 22°C (72°F), and a maximum reaching 34°C (93°F). Precipitation in April is lower, at 117 mm (4.6 in) over 18 days, accompanied by a more comfortable humidity level of 64%. For a more detailed look, you can visit Lang Son weather in April.
September and May both exhibit warm temperatures, with September's average at 26°C (80°F) similar to May's. However, September tends to experience slightly higher maximum temperatures, peaking at 34°C (94°F) compared to May's 35°C (96°F). Precipitation is more pronounced in September, with 198 mm (7.8 in) of rain over 22 days versus May's 179 mm (7.1 in) across the same number of days. Additionally, September is more humid, sitting at 82%, while May maintains a lower humidity level of 73%. For a more detailed look at May weather, visit Lang Son weather in May.
In comparing the weather between September and June, September tends to be slightly cooler, with an average temperature of 26°C (80°F) compared to June's warmer average of 28°C (83°F). Both months experience high humidity, hovering around 81% in June and 82% in September. While June boasts a higher maximum temperature, reaching up to 37°C (100°F), September's maximum reaches 34°C (94°F). Precipitation is more substantial in June, totaling 235 mm (9.2 in) over 21 days, compared to September's 198 mm (7.8 in) over 22 days. For a detailed look at June weather, visit Lang Son weather in June.
In comparing the weather of September and July, we see some notable differences. September experiences slightly cooler temperatures, with a minimum of 19°C (67°F) and an average high of 34°C (94°F), compared to July's minimum of 23°C (73°F) and an average maximum of 35°C (96°F). While both months have significant rainfall, July tends to be wetter, with 243 mm (9.6 in) of precipitation over 23 days, versus September's 198 mm (7.8 in) across 22 days. Additionally, humidity levels are higher in July at 90%, compared to September's 82%. For more detailed insights, you can check Lang Son weather in July.
In September, the weather shows a slight decrease in temperature, with minimums around 19°C (67°F) compared to August's minimum of 22°C (72°F). The average temperatures are somewhat similar, with 26°C (80°F) in September and 27°C (81°F) in August, while maximum temperatures remain nearly on par, reaching 34°C (94°F) in September and 35°C (96°F) in August. However, September experiences significantly more rainfall, accumulating 198 mm (7.8 in) over 22 rainy days, compared to August's 346 mm (13.6 in) over 28 days. Humidity in September is slightly lower at 82% compared to 89% in August. For more detailed insights on August's climate, visit Lang Son weather in August.
In September, the weather is warmer, with average temperatures around 26°C (80°F) and maximums reaching up to 34°C (94°F). However, it also experiences higher humidity at 82% and significant rainfall, totaling 198 mm (7.8 in) over 22 days. In contrast, October brings cooler temperatures, with averages dropping to 23°C (73°F) and maximums at 32°C (90°F). The month is drier, with 170 mm (6.7 in) of precipitation over 15 days and slightly less humidity at 77%. For more detailed information, check out Lang Son weather in October.
September and November present distinct weather contrasts. In September, temperatures range from a mild 19°C (67°F) to a scorching 34°C (94°F), with an average of 26°C (80°F). This month experiences significant rainfall, totaling 198 mm (7.8 in) over 22 days, accompanied by high humidity at 82%. In contrast, November sees cooler temperatures, with a minimum of 9°C (48°F) and a maximum of 30°C (86°F), averaging 20°C (68°F). Rainfall drops dramatically to 39 mm (1.6 in) over just 9 days, and humidity decreases to a more comfortable 72%. For more detailed information, you can check Lang Son weather in November.
September and December present stark contrasts in weather conditions. In September, temperatures range from a minimum of 19°C (67°F) to a maximum of 34°C (94°F), with an average of 26°C (80°F). This month is marked by significant rainfall, totaling 198 mm (7.8 in) over 22 days, contributing to a high humidity level of 82%. In contrast, December sees cooler temperatures, with a minimum of 4°C (40°F) and a maximum of 28°C (82°F), averaging 15°C (60°F). Precipitation decreases dramatically to 51 mm (2.0 in) over just 9 days, and humidity drops to a more comfortable 71%. For more detailed insights, check out Lang Son weather in December.
As September rolls in, Lang Son experiences a notable transition in weather dynamics compared to previous months. With an average temperature hovering around 26°C (80°F), the warmth persists, yet it is juxtaposed by a higher humidity level reaching 82%, giving a tropical feel to the air. Rainfall becomes more prominent, with 22 rainy days and a total of 198 mm (7.8 in) of precipitation, making this month one of the wettest in the region. This substantial moisture sets September apart, often adding a refreshing coolness after the heat of summer, transforming the landscape into a lush oasis. For more insights into the climate of Lang Son throughout the year, be sure to check out Lang Son Climate.