Last updated: August 27, 2025
September in Rotterdam unveils a vibrant transition from summer to autumn, showcasing a range of temperatures that peak at a warm 31°C (87°F) and dips to a crisp 4°C (40°F) at night. On average, the month settles around a mild 15°C (60°F), offering pleasant days. With 75 mm (3.0 in) of rainfall spread across 11 days, there's a fair chance of experiencing refreshing showers, contributing to an impressive 82% humidity that envelops the city. Whether basking in the sun or enjoying a cozy indoor atmosphere during the rain, September's weather in Rotterdam presents a tapestry of seasonal charm.
In September, Rotterdam experiences a transition into autumn, with temperatures gradually cooling down after the summer heat. The month sees a minimum temperature of around 4°C (40°F), averaging a comfortable 15°C (60°F), while highs can still reach a pleasant 31°C (87°F). This fluctuation reflects the tail end of summer's warmth, making September an ideal time to enjoy outdoor activities before the chill of autumn sets in. As the month progresses, the days become noticeably shorter, hinting at the seasonal change, yet the lingering warmth ensures that visitors can relish both the crispness of early fall and the warmth of late summer.
September in Rotterdam sees a moderate precipitation level, with an average of 75 mm (3.0 in) spread over 11 days. This marks a slight decrease compared to the wetter summer months, yet it remains significantly higher than earlier spring months. The transition from summer to autumn showcases a beautifully balanced climate, where occasional showers are enriched by lingering warmth. As the city starts to prepare for the more substantial rains of October, September acts as a gentle reminder of the changing seasons, maintaining a lively atmosphere while embracing the richness of rainfall.
In September, Rotterdam experiences a notable shift as humidity levels stabilize at 82%, aligning closely with the drier summer months of June and July. This slight increase from August's 76% indicates the onset of autumn, where cooler temperatures begin to reclaim the city. As the year progresses, humidity tends to rise again, peaking in the winter months with 91% in January and 92% in November and December. This trend emphasizes Rotterdam's overall humid climate, marked by relatively high levels throughout the year, yet punctuated by a brief summer reprieve.
As summer fades into autumn, the UV Index in Rotterdam experiences a gradual decline. In September, the UV Index returns to a moderate level of 5, similar to what is recorded in April and October, indicating a burn time of approximately 30 minutes. This transition marks a shift from the very high indices of July and June, where sun exposure required vigilant protection. With the UV Index dropping, outdoor enthusiasts can enjoy the crisp autumn air while still being mindful of UV exposure. For detailed information on UV levels throughout the year, visit Rotterdam UV Index.
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As the summer warmth begins to wane, September in Rotterdam brings a delightful end to the sun-soaked days with 329 hours of sunshine. This month stands out as a transition, revealing a gentle decline from the peak brightness of July, which boasts 425 hours. While the sun shines brightly, September's light is notably softer than the vibrant height of summer, yet it still offers a notably generous amount compared to the dimming months ahead, like the dreariness of November, with its mere 195 hours. As autumn approaches, the increasing cloud coverage is evident, but the lingering sunshine provides a beautiful backdrop for outdoor activities and reflection before winter sets in. Overall, September encapsulates the golden glow of late summer, perfectly bridging the warmth of past months with the cooler days looming on the horizon.
September in Rotterdam offers a moderate chance of sunny weather, with the likelihood of sunshine sitting around 32%. This percentage reflects a slight decline from the sunny highs of spring, where April peaks at 40%, but remains consistent with the summer months, which hover around the lower 30s. As summer transitions to autumn, the sunshine probability begins to taper off gradually, reminiscent of the crispness in the air. While September may not boast the sunniest days compared to earlier months, it still holds its own, inviting outdoor activities during the pleasant early fall days. So, if you’re planning a visit, keep your sunglasses handy!
As summer gives way to autumn in September, daylight in Rotterdam begins to slowly recede, offering around 12 hours of illumination—a gentle transition from the sun-drenched days of June and July, which basked in a generous 16 hours. This month marks the start of a gradual decline in daylight, following the peak of summer brightness, as the city anticipates the shorter days of fall and winter. After enjoying 14 hours in August, September's sunlight lingers longer than the dark days of October and November, but hints at the cozy relaxation of the colder months ahead, creating a unique seasonal rhythm that shapes life in Rotterdam.
As September graces Rotterdam, the average wind speed tends to slow down to a gentle 3.4 m/s (8 mph), reflecting a noticeable decline from the bustling summer months. With the wind easing off compared to August's 4.1 m/s (9 mph) and preceding months like June and July, this change heralds the transition into autumn. Interestingly, throughout the year, wind speeds generally fluctuate, peaking in October at 4.8 m/s (11 mph), but September's calmness sets a serene tone, inviting residents and visitors alike to enjoy the city's picturesque scenery with a fresh, crisp breeze. As nature shifts gears, the softer winds beckon for cozy gatherings and leisurely strolls along the waterfront.
Weather in Rotterdam varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Rotterdam, focusing on differences in temperature, rainfall, humidity, and UV levels.
In September, temperatures range from a cool minimum of 4°C (40°F) to a warm maximum of 31°C (87°F), with an average of 15°C (60°F). This month experiences about 75 mm (3.0 in) of precipitation over approximately 11 days, accompanied by a moderate humidity level of 82%. In contrast, January experiences much colder conditions, with temperatures dropping to a minimum of -8°C (19°F) and peaking at a maximum of 14°C (58°F), averaging around 5°C (41°F). The precipitation is slightly lower at 57 mm (2.3 in) but spans 12 days, with a higher humidity of 91%. For a closer look at January weather, visit Rotterdam weather in January.
September and February present contrasting weather conditions in many ways. In September, temperatures range from a minimum of 4°C (40°F) to a maximum of 31°C (87°F), with an average of 15°C (60°F), making it generally warmer than February, which experiences a minimum of -9°C (15°F) and a maximum of 18°C (65°F) with an average of 5°C (42°F). Additionally, September sees slightly higher precipitation at 75 mm (3.0 in) over 11 days, compared to February's 65 mm (2.6 in) spread across 12 days. Humidity levels are also notably different; September’s 82% contrasts with February’s elevated 89%. For a closer look at the climate during this chilly month, you can check Rotterdam weather in February.
In comparing the weather of September and March, notable differences emerge in both temperature and precipitation. September tends to be much warmer, with average temperatures ranging from a minimum of 4°C (40°F) to a maximum of 31°C (87°F), while March experiences colder temperatures, with a minimum of -8°C (18°F) and a maximum of 21°C (71°F). Despite slightly lower precipitation in March at 69 mm (2.7 in) over 14 days, the humidity remains high in both months, with March reaching 87% compared to September's 82%. For more information on the specific weather conditions in March, you can check Rotterdam weather in March.
In comparing the weather of September and April, September generally presents warmer temperatures with a minimum of 4°C (40°F) and an average of 15°C (60°F), reaching a maximum of 31°C (87°F). In contrast, April sees cooler conditions, starting with a minimum of -1°C (30°F) and averaging at 10°C (50°F), peaking at 27°C (81°F). Additionally, September has higher humidity at 82% and more precipitation, totaling 75 mm (3.0 in) over 11 days, compared to April’s 44 mm (1.7 in) spread over 9 days. For more details on April weather, visit Rotterdam weather in April.
In comparing the weather between September and May, both months experience similar maximum temperatures of 31°C (87°F), but September boasts a slightly warmer average temperature of 15°C (60°F) compared to May's 13°C (56°F). September also sees a higher minimum temperature of 4°C (40°F) versus May's cooler 1°C (35°F). In terms of precipitation, September has a bit more rainfall, with 75 mm (3.0 in) over 11 days, while May records 65 mm (2.5 in) over 12 days. Notably, both months share the same humidity level of 82%, creating a consistently humid atmosphere. For more details, check out Rotterdam weather in May.
When comparing the weather in September and June, both months exhibit relatively warm temperatures, with average highs close to 31°C (87°F) in September and 32°C (89°F) in June. However, September tends to have slightly lower minimum temperatures, starting at around 4°C (40°F) compared to June's 7°C (45°F). Both months have similar humidity levels at 82%, contributing to a muggy feel, but they differ slightly in precipitation, with September receiving 75 mm (3.0 in) over 11 days and June getting 72 mm (2.8 in) over 10 days. For more detailed insights into the weather patterns during this time, you can check Rotterdam weather in June.
In comparing the weather between September and July, September has a broader temperature range, with a minimum of 4°C (40°F) and a maximum of 31°C (87°F), resulting in an average temperature of 15°C (60°F). In contrast, July consistently experiences warmer temperatures, with a minimum of 8°C (47°F) and a maximum of 38°C (101°F), leading to an average of 18°C (65°F). While July sees slightly less precipitation (68 mm) over more days (13) compared to September's 75 mm over 11 days, both months are characterized by high humidity levels, with September at 82% and July at 80%. For a more detailed look at July weather, you can visit Rotterdam weather in July.
In comparing the weather between August and September, September offers a notable shift in temperatures, with a minimum of 4°C (40°F), compared to August's milder minimum of 8°C (48°F). The average temperature in September is 15°C (60°F), which is lower than August's average of 18°C (65°F). Both months experience similar maximum temperatures, with September reaching up to 31°C (87°F) and August slightly higher at 33°C (93°F). Precipitation is also slightly less in September at 75 mm (3.0 in) over 11 days, compared to August's 84 mm (3.3 in) over 14 days. Additionally, September has a higher humidity level at 82%, compared to August's 76%. For a detailed look at August weather, you can check Rotterdam weather in August.
September and October bring notable changes in weather patterns. In September, temperatures range from a minimum of 4°C (40°F) to a maximum of 31°C (87°F), with an average of 15°C (60°F). The month sees about 75 mm (3.0 in) of precipitation over 11 days and an average humidity of 82%. In contrast, October presents a cooler climate, with temperatures dropping to a minimum of 2°C (36°F) and peaking at 25°C (78°F), averaging 12°C (55°F). This month also experiences slightly higher precipitation at 92 mm (3.6 in) across 16 days, accompanied by an increase in humidity to 89%. For more detailed information, check out Rotterdam weather in October.
In September, the weather is generally warmer, with temperatures ranging from a minimum of 4°C (40°F) to a maximum of 31°C (87°F) and an average of 15°C (60°F). The month experiences a fair amount of rain, totaling 75 mm (3.0 in) over 11 days, with humidity levels around 82%. In contrast, November brings much cooler temperatures, with a minimum of -2°C (29°F), an average of 8°C (46°F), and a maximum of 18°C (65°F). Although November has slightly less precipitation at 56 mm (2.2 in), it has a higher number of rainy days at 12 and a humidity level of 92%. For more detailed information, you can check out Rotterdam weather in November.
September and December present contrasting weather patterns. In September, temperatures can range from a mild 4°C (40°F) at night to a warm 31°C (87°F) during the day, with an average of 15°C (60°F). The month experiences about 75 mm (3.0 in) of precipitation over 11 days, and humidity levels sit at 82%. In stark contrast, December brings colder temperatures, with lows dropping to -4°C (25°F) and highs peaking at 14°C (57°F), resulting in an average of just 6°C (43°F). This month sees increased precipitation, totaling around 90 mm (3.5 in) across 17 days, alongside higher humidity at 92%. For more details on December weather, you can refer to Rotterdam weather in December.
As summer transitions into autumn, September in Rotterdam presents a unique blend of warm and cool weather. Daytime temperatures can reach up to 31°C, but it's common for the average to hover around a comfortable 15°C, making it a month of contrasts. While occasional warm days linger, the nights can drop to cooler levels, reminding us of the impending fall. With nearly 75 mm of precipitation spread across about 11 days, this month becomes one of the wetter periods, contributing to the city's lush scenery. High humidity levels at 82% can also make the air feel heavier. For those seeking to understand the overall climate, this transitional month is definitely a precursor to the cooler temperatures ahead, making it distinct from both the previous summer and the forthcoming autumn months. To explore more about what to expect throughout the year, check out Rotterdam Climate.