Last updated: August 21, 2025
Surabaya, Indonesia, in September experiences a warm and humid climate, with maximum temperatures reaching 31°C (89°F) and an average of 23°C (75°F). The weather is characterized by minimum temperatures dipping to 17°C (62°F), providing a comfortable range for residents and visitors alike. While the month brings an average precipitation amount of 49 mm (1.9 in) over approximately 10 rainy days, the humidity remains relatively high at 72%, creating a tropical feel. This combination of warmth and moisture sets the stage for vibrant local flora and a lively atmosphere throughout the city.
In September, Surabaya experiences a delightful balance in temperatures, with minimums around 17°C (62°F) and averages settling comfortably at 23°C (75°F). As summer extends its grip, the maximum temperature reaches 31°C (89°F), marking it as one of the warmer months of the year. Notably, September continues the gradual trend of rising temperatures observed since July, while also maintaining the stable, tropical feel characteristic of Surabaya’s climate. As the month progresses, residents and visitors alike can expect warm days and pleasant evenings, perfect for evening strolls or exploring the vibrant city life. Overall, this month encapsulates the essence of tropical living with its inviting warmth and comfortable averages.
In September, Surabaya experiences a noticeable decline in precipitation, with only 49 mm (1.9 in) of rainfall spread across 10 days. This marks a significant reduction compared to the earlier months of the year, reflecting the dry season's ongoing influence. Following the heavy rains of March and November, September stands out for its relative dryness, as the city transitions from the peak monsoon months. The shift from an intense wet season to milder rainfall is evident, creating a brief respite that many locals and visitors alike enjoy before the rains return in October.
September marks a noticeable shift in Surabaya's humidity levels, as the month experiences a drop to 72%, the lowest point since April. This decline follows a gradual decrease from the peak humidity of 87% seen in February. While the humidity typically starts high at the beginning of the year, it trends downwards through the summer months, reaching a relative low in September. The warmer months of June and July display a more stable and lower humidity range, around 79% to 81%, but September's dip suggests a gentle transition towards the more humid conditions of October, which rises to 74%. This seasonal fluctuation highlights Surabaya's tropical climate, where fluctuations in humidity are a natural part of the year's rhythm.
In Surabaya, Indonesia, the UV Index remains consistently high throughout the year, particularly in September, where it registers an index of 14, classified as extreme, with a burn time of just 10 minutes. This trend of intense UV radiation is evident as the index fluctuates between 13 and 16 from January to October, encouraging residents and visitors alike to take necessary precautions against sun exposure. Given that every month reflects an extreme exposure category, it's crucial to remain vigilant about sun safety. To learn more about the UV Index in Surabaya, visit Surabaya UV Index.
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September in Surabaya, Indonesia, ushers in a delightful continuation of abundant sunshine, boasting 310 hours of sunlight. This makes it one of the sunniest months of the year, paralleling October's hours while maintaining a strong glow that began in the peak of summer. As the city basks in this radiant light, it reflects a slight decline from the record high of 322 hours in August but remains robustly above the 300-hour mark. The trend of increasing sunlight from the early months of the year culminates in this bright September, making it a vibrant time for outdoor activities and cultural celebrations, as the city enjoys its tropical climate.
In Surabaya, Indonesia, September marks a transitional period as the likelihood of sunny weather remains steady at 25%. This is a notable trend compared to the peak of sunny days observed in July at 39% and the following months where the chances noticeably decline. August offers a similar promise with 32% likelihood, but as the sunny days of summer wane, September maintains a consistent chance, allowing residents and visitors to enjoy a mix of sun interspersed with occasional rain. This stabilizing figure hints at the tail end of the dry season, creating a comfortable atmosphere before the wetter months set in.
In Surabaya, Indonesia, the daylight duration exhibits a fascinating consistency throughout the year. From January to March, the city enjoys a steady 12 hours of daylight, creating a perfect backdrop for vibrant activities. As the months transition into April through August, the days shorten slightly to 11 hours, a reflection of the changing seasons and cooler periods. However, come September, sunlight reasserts its dominance, bringing back 12 hours of brilliant daylight, which continues through October, November, and into December. This rhythmic cycle of daylight not only shapes daily life but also highlights Surabaya's tropical climate, where the sun remains a steadfast companion throughout the year.
September in Surabaya, Indonesia, brings a refreshing breeze, with average wind speeds reaching 1.6 m/s (4 mph)—the same brisk pace celebrated in August. This consistent airflow hints at the transitional nature of the month, as the city begins to shift towards the drier season. Following a summer marked by gentle winds, September's steady gusts infuse the atmosphere with vibrant energy, making it an ideal time for outdoor activities. As the year progresses into October, the winds slightly taper off, but the warm embrace of the September breezes lingers in the air, reminding residents of the exhilarating sway before the calm of the later months.
Weather in Surabaya varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Surabaya, focusing on differences in temperature, rainfall, humidity, and UV levels.
September typically experiences warm temperatures, with a minimum of 17°C (62°F) and a maximum of 31°C (89°F). The average temperature hovers around 23°C (75°F) and brings moderate humidity levels at 72%. Rainfall during this month is comparatively light, totaling about 49 mm (1.9 in) over approximately 10 days.
In contrast, January is characterized by slightly higher minimum temperatures at 19°C (67°F) and a maximum of 30°C (86°F), while the average remains nearly the same as September at 23°C (74°F). However, January sees a significant increase in precipitation, reaching 461 mm (18.2 in) across about 25 days, and higher humidity levels at 84%. This makes January a notably wetter month compared to September. For more details on January weather, visit Surabaya weather in January.
In comparing the weather conditions of September and February, we notice several distinct differences. September tends to have slightly cooler temperatures, with a minimum of 17°C (62°F) and a maximum of 31°C (89°F), while February remains warmer with a minimum of 19°C (67°F) and a maximum of 30°C (86°F). Despite having similar average temperatures, February experiences significantly higher rainfall, with 485 mm (19.1 in) of precipitation over 28 days, compared to September's 49 mm (1.9 in) over just 10 days. Additionally, February's humidity is higher at 87%, compared to September's 72%, making it feel more humid during the month. For a detailed look at February's weather, you can visit Surabaya weather in February.
When comparing the weather in September and March, we can see some notable differences. September enjoys warmer temperatures, ranging from a minimum of 17°C (62°F) to a maximum of 31°C (89°F), with an average of 23°C (75°F). In contrast, March has slightly higher minimum temperatures at 19°C (66°F) and averages around the same 23°C (74°F), but it has a cooler maximum temperature of 30°C (86°F).
However, March is significantly wetter, with a staggering 502 mm (19.8 in) of precipitation over 30 days, compared to September's 49 mm (1.9 in) over just 10 days. This increase in rainfall also contributes to higher humidity levels in March, averaging 85% compared to September's 72%. For more detailed insights, you can check Surabaya weather in March.
In comparing the weather of September and April, both months share similar minimum temperatures around 17°C (62°F-64°F) and average temperatures close to 23°C (75°F). However, April tends to be slightly warmer with an average temperature of 24°C (75°F) and a maximum of 30°C (87°F), while September has a maximum of 31°C (89°F). Notably, April experiences significantly higher precipitation, with 332 mm (13.1 in) spread over 27 days, compared to September's 49 mm (1.9 in) over just 10 days. The humidity is also higher in April at 82% versus 72% in September, making the latter month feel relatively drier. For more detailed insights, you can check Surabaya weather in April.
In comparing the weather between September and May, we see some distinct differences. September tends to be slightly warmer with average temperatures ranging from a minimum of 17°C (62°F) to a maximum of 31°C (89°F), while May's temperatures are a bit cooler, with averages from 18°C (65°F) to 30°C (87°F). However, May experiences significantly more precipitation, with 163 mm (6.4 in) over 18 days compared to September's 49 mm (1.9 in) across only 10 days. Additionally, May has a higher humidity level at 81%, compared to September's 72%. For more detailed insights, you can check out Surabaya weather in May.
In comparing the weather of June and September, we notice some similarities and differences. Both months experience a minimum temperature of around 17°C (62°F) and a maximum reaching 31°C (89°F in September and 88°F in June). However, September averages slightly lower at 23°C (75°F) compared to June's average of 24°C (75°F). Precipitation is a little lower in September, with 49 mm (1.9 in) over 10 days, while June has 59 mm (2.3 in) over 12 days, indicating that June is slightly wetter. Additionally, humidity levels are higher in June at 81%, compared to September's 72%. For a more in-depth look at June weather specifics, visit Surabaya weather in June.
In terms of weather, September tends to be slightly warmer than July, with average temperatures hovering around 23°C (75°F) in both months, but September sees maximum temperatures reaching up to 31°C (89°F) compared to July's 30°C (87°F). Rainfall also plays a role in the differences; September receives more precipitation, totaling 49 mm (1.9 in) over 10 days, while July experiences just 28 mm (1.1 in) over 5 days. Additionally, humidity levels are marginally higher in July at 79%, compared to September's 72%. For a more detailed overview, you can visit Surabaya weather in July.
In comparing the weather between September and August, both months exhibit similar temperature ranges, with September having a minimum temperature of 17°C (62°F) and an average of 23°C (75°F), while August has slightly lower minimum temperatures of 16°C (60°F) and the same average of 23°C (73°F). The maximum temperatures are consistent as well, peaking at 31°C (89°F) in September and 31°C (88°F) in August. However, September experiences more precipitation, totaling 49 mm (1.9 in) over 10 days, compared to August, which sees only 26 mm (1.0 in) across 6 days. Additionally, September has a marginally lower humidity at 72% in contrast to August's 76%. For a more detailed look at August's weather patterns, you can visit Surabaya weather in August.
In September, the weather tends to be warm with an average temperature of 23°C (75°F) and maximums reaching up to 31°C (89°F). The month experiences about 49 mm (1.9 inches) of precipitation over roughly 10 days, with a humidity level of 72%. In contrast, October sees a slight increase in temperature, with a minimum of 18°C (65°F) and an average of 24°C (75°F), peaking at 33°C (91°F). However, this month is notably wetter, with precipitation totaling 132 mm (5.2 inches) over 19 days and humidity rising to 74%. For more detailed information, you can check Surabaya weather in October.
In comparing the weather between September and November, a noticeable shift occurs in both temperature and precipitation patterns. September typically sees warmer temperatures, with a minimum of 17°C (62°F) and a maximum of 31°C (89°F), averaging around 23°C (75°F). The month also experiences relatively moderate rainfall, with 49 mm (1.9 in) of precipitation over about 10 days and humidity levels around 72%.
In contrast, November brings slightly higher temperatures, with a minimum of 18°C (65°F) and a maximum of 33°C (91°F), while the average remains at 24°C (75°F). However, this month also delivers a significant increase in precipitation, totaling 377 mm (14.9 in) across approximately 25 days, and a rise in humidity to 78%. This dramatic change underscores the transition into the wet season. For more detailed information, check Surabaya weather in November.
September and December in Surabaya present notable contrasts in weather. While September enjoys warmer temperatures with a minimum of 17°C (62°F) and an average of 23°C (75°F), December sees slightly higher minimum temperatures at 19°C (67°F) but maintains a similar average of 23°C (74°F). Both months experience high humidity, with December reaching 78% compared to September's 72%. However, December brings significantly more rainfall, totaling 464 mm (18.3 in) over 30 days, compared to September's 49 mm (1.9 in) across 10 days. For more detailed information, you can visit Surabaya weather in December.
As September rolls into Surabaya, the weather showcases a delightful transition, offering a refreshing shift from the sweltering heat of the preceding months. With comfortable average temperatures hovering around a pleasant 23°C, this month presents a reprieve, featuring maximums that still warm the air without overwhelming humidity levels. While light rains sprinkle the city on about ten days, contributing to a charming atmosphere, the overall precipitation is relatively mild compared to the wetter months ahead. This combination creates a perfect backdrop for exploring the city. For a deeper dive into the climate nuances throughout the year, visit Surabaya Climate.