September Weather in Aalst, Belgium

Last updated: August 21, 2025

In Aalst, Belgium, September brings a transitional climate marked by fluctuating temperatures. The month showcases a maximum of 32°C (90°F), offering warm days, while evenings can dip to a cool 4°C (40°F), resulting in an average temperature of 16°C (60°F). Though sunshine may warm the days, rainfall is a frequent visitor, with 52 mm (2.1 in) of precipitation spread over 9 days, contributing to a humidity level of 82%. This combination creates a unique atmosphere that beautifully blends the tail end of summer with the onset of autumn, perfect for outdoor activities and exploration in this charming Belgian locale.

September Temperature in Aalst

In Aalst, Belgium, September marks a transition into more moderate temperatures after the intense summer heat. With a minimum temperature of around 4°C (40°F) and an average reaching 16°C (60°F), the month offers a comfortable reprieve from the sweltering highs of August. Temperatures can still soar, peaking at 32°C (90°F), making it a delightful time for outdoor activities. As summer fades, the city experiences a balance of warmth and crispness, creating a perfect backdrop for the beginning of autumn. This shift not only enriches the scenery but also invites locals and visitors alike to embrace the changing season, highlighting September as a vibrant yet serene month in Aalst.

September Weather in Aalst: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Aalst, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Aalst, September typically has an average temperature of {2}°C ({3}°F), with highs reaching up to {4}°C ({5}°F) and lows dropping to around {6}°C ({7}°F).
JanFebMarAprMayJunJulAugSepOctNovDec404245505765666660554642
Data source: Temperature data for Aalst generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Aalst

In September, Aalst experiences a relatively mild decrease in precipitation, averaging 52 mm (2.1 in) over nine days of rainfall. This month often transitions the city from the wetter summer months into the drier autumn season, showcasing a notable contrast from August's peak of 73 mm. With an average of 2.1 inches, September's precipitation is less than that of the previous months, yet it remains significant enough to keep the landscape lush. As the year progresses, October is expected to see a resurgence in rain, further emphasizing the seasonal shifts in Aalst's climate. Overall, September marks a gentle nod to the changing seasons, preparing residents for the upcoming briskness of fall.

September Precipitation Trends in Aalst

The chart displays monthly precipitation patterns in Aalst, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Aalst, September typically receives around {2} mm ({3} inches) of precipitation spread over approximately {4} days.
JanFebMarAprMayJunJulAugSepOctNovDec626569396063667352815389
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Aalst

In Aalst, Belgium, the month of September experiences a resurgence in humidity, returning to 82% after the summer months. This slight uptick follows a trend of declining humidity from the winter's highs of 91% in January down to a summer low of 76% in August, as the season transitions. The percentages suggest a seasonal pattern where humidity peaks in colder months and begins to recover in the early autumn, setting the stage for the wet and chilly October ahead. The rhythm of humidity in Aalst emphasizes a gradual return to the moisture-rich climate characteristic of the later autumn months, making September a pivotal point in this annual cycle.

September Average Humidity in Aalst

This chart illustrates the average monthly humidity levels in Aalst, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Aalst is approximately {2}%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec91%89%87%85%82%82%80%76%82%89%92%92%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Aalst

In September, the UV Index in Aalst, Belgium, settles at a moderate level of 5, providing a respite from the peak summer sun. Following the very high indices of July and August, the drop reflects a transition to milder autumn weather, with a burn time of 30 minutes for unprotected skin. This decline signifies a notable trend from previous months when the exposure risk was significantly higher. As autumn approaches, residents and visitors alike can enjoy the outdoors more safely, though it's still wise to stay vigilant about sun protection. Explore the details further at Aalst UV Index.

Maximum UV Index Levels in Aalst for September

The chart shows the monthly maximum UV Index (UVI) for Aalst in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Aalst typically reaches {2}, which falls under the {3} exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec124578875321
Data source: Aalst September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

September Sunshine in Aalst

As summer gracefully transitions into autumn, September in Aalst, Belgium, offers a delightful blend of warmth and light, accumulating 323 hours of sunshine. This is a noticeable dip from the sun-drenched peak of 415 hours in July, but remains significantly vibrant compared to the lower light of the upcoming months. With the days gradually shortening, September still retains a lush brightness, inviting both locals and visitors to savor the lingering warmth before the cooler October arrives with its 243 hours of sunshine. Such patterns reflect not only the shifting seasons but also the beauty of Aalst's autumnal charm, making September a perfect time to relish the waning sun.

Monthly Sunshine Duration in Aalst: September Highlighted

The September sunshine duration represents the total number of hours Aalst experiences direct sunlight during the month of September, excluding cloudy or obstructed periods. This chart compares the sunshine duration of September with the other months of the year.
JanFebMarAprMayJunJulAugSepOctNovDec120h204h274h351h400h407h415h386h323h243h196h149h
Data source: Aalst September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Aalst During September

In Aalst, Belgium, September presents a moderate probability of sunny weather, with a 34% chance of sunshine, mirroring the trends seen in the summer months of July and August. This slight increase from the spring's peak in April, when there is a 48% chance of sun, indicates that while September still enjoys decent daylight, the gradual transition into autumn results in a notable decrease in sunny days. As the year progresses, the likelihood of sun dips significantly, with October and November witnessing drops to 30% and 22%, respectively. Therefore, while September holds onto the summery spirit for a little longer, it stands as a gentle reminder of the seasonal shift ahead.

Percentage of Sunny Days in September in Aalst

The chart illustrates the percentage of sunny days in Aalst throughout the year, with September highlighted. It highlights the variation in sunshine across each month and provides an overview of the typical frequency of sunny days, offering insights into how often Aalst experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec12%30%39%48%34%34%34%31%34%30%22%15%
Data source: Aalst September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Aalst in September

As September arrives in Aalst, Belgium, the daylight begins to wane, offering approximately 12 hours of sunshine. This marks a gradual transition from the long, sun-drenched days of summer, where June shines at an impressive 16 hours, to the more muted light of autumn. Following the vibrant 15 hours of May and the still generous 14 hours of August, September's daylight serves as a gentle reminder of the forthcoming shift towards shorter weeks as we head into October, where daylight dwindles to 10 hours. This pattern highlights a natural ebb and flow in daylight, painting a vivid portrait of the changing seasons in this charming Belgian town.

Average Daylight Hours in Aalst for September

The chart illustrates the variation in daylight duration in Aalst throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec8h 29m10h 1m11h 55m13h 51m15h 32m16h 25m15h 57m14h 26m12h 34m10h 38m8h 55m8h
Data source: Aalst daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Aalst

As September unfolds in Aalst, Belgium, the wind begins to whisper a gentle lull, with an average speed of 3.0 m/s (7 mph). This marks a noticeable decrease compared to the summer months, where breezes lingered around 3.2 to 3.4 m/s. This gradual calming reflects a transitional shift in the season, as the vibrant energy of summer winds down. It's interesting to note that September's wind speed is the lowest of the year, underscoring the tranquility that coats the landscape with the onset of autumn. Looking ahead, the gusts are set to pick up again in October, reminding us that nature's rhythms are ever-changing yet beautifully predictable.

Average September Wind Speed in Aalst

The chart displays monthly wind speed patterns in Aalst, with values for each month shown alongside September's data, which is highlighted for easy comparison. It illustrates the average wind speed, offering insights into how September's wind conditions compare to the rest of the year.
JanFebMarAprMayJunJulAugSepOctNovDec4.24.43.93.54.22.83.23.43.0 m/s4.23.24.0
Data source: Aalst September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Aalst Compares to Other Months

Weather in Aalst varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Aalst, focusing on differences in temperature, rainfall, humidity, and UV levels.

September and January present contrasting weather conditions. In September, temperatures range from a minimum of 4°C (40°F) to a maximum of 32°C (90°F), with an average of 16°C (60°F). This month sees relatively lower precipitation at 52 mm (2.1 in) over 9 days and a humidity level of 82%. In contrast, January experiences colder temperatures, with a minimum of -6°C (21°F) and a maximum of 14°C (58°F), averaging only 4°C (40°F). January also has slightly higher precipitation at 62 mm (2.5 in) spread over 12 days, while humidity rises to 91%. For more details on the January weather specifically, refer to Aalst weather in January.

September and February present stark contrasts in weather. In September, temperatures range from a minimum of 4°C (40°F) to a maximum of 32°C (90°F), with an average of 16°C (60°F). The month experiences moderate precipitation of 52 mm (2.1 in) over 9 days, accompanied by a relatively high humidity of 82%. In contrast, February sees much colder weather, with temperatures ranging from a minimum of -11°C (13°F) to a maximum of 18°C (65°F) and an average of 6°C (42°F). This month also has higher precipitation at 65 mm (2.6 in) over 12 days, and humidity levels rise to 89%. For more detailed insights, you can explore Aalst weather in February.

In September, temperatures in Aalst typically range from a pleasant minimum of 4°C (40°F) to a warm maximum of 32°C (90°F), with an average of 16°C (60°F). This month experiences relatively low precipitation of 52 mm (2.1 in) spread over 9 days and has a humidity level of 82%. In contrast, March brings much cooler temperatures, with a minimum of -7°C (19°F) and a maximum of 23°C (73°F), averaging 7°C (46°F). March sees increased precipitation at 68 mm (2.7 in) over 14 days and a slightly higher humidity level of 87%. To learn more about the weather specifics in March, check out Aalst weather in March.

Comparing the weather in September and April reveals notable differences in temperature and humidity. In September, temperatures range from a minimum of 4°C (40°F) to a maximum of 32°C (90°F), with an average of 16°C (60°F), while April experiences cooler temperatures, with a minimum of -3°C (28°F) and a maximum of 27°C (80°F), averaging around 10°C (51°F). Precipitation is slightly higher in September at 52 mm (2.1 in) compared to 39 mm (1.5 in) in April, with both months seeing rain over 9 days. Humidity is similar, with September at 82% and April slightly higher at 85%. For more details, check out Aalst weather in April.

In September, temperatures range from a minimum of 4°C (40°F) to a maximum of 32°C (90°F), with an average of 16°C (60°F), while May sees slightly cooler temperatures, with a minimum of 1°C (34°F), an average of 14°C (57°F), and a maximum of 30°C (87°F). Both months experience high humidity levels of 82%, creating a muggy atmosphere. However, September receives 52 mm (2.1 in) of precipitation over about 9 days, compared to May's slightly higher precipitation of 59 mm (2.3 in) over 12 days. For more details on the weather conditions in May, you can visit Aalst weather in May.

In comparing the weather of September and June, both months showcase similar maximum temperatures peaking at around 32°C (90°F). However, September experiences a slightly cooler average temperature of 16°C (60°F) compared to June's 18°C (65°F). While both months see an equal number of precipitation days at 9, June typically has higher rainfall, amounting to 63 mm (2.5 in) versus September's 52 mm (2.1 in). Humidity levels remain constant at 82% in both months, creating a similarly muggy atmosphere. For more detailed insights, you can refer to Aalst weather in June.

When comparing the weather in September and July, several key differences emerge. September experiences cooler temperatures, with a minimum of 4°C (40°F) and an average of 16°C (60°F), while July sees warmer conditions, starting at a minimum of 8°C (47°F) and averaging 19°C (66°F). The peak temperatures in July can reach a scorching 39°C (102°F), significantly higher than September's maximum of 32°C (90°F). Additionally, July has slightly more precipitation, totaling 66 mm (2.6 in) over 11 days, compared to September's 52 mm (2.1 in) over 9 days. Humidity remains relatively high in both months, with September at 82% and July at 80%. For more specific details about July's weather, you can refer to this link: Aalst weather in July.

In comparing the weather between September and August, September experiences a cooler temperature range, with a minimum of 4°C (40°F) compared to August's minimum of 8°C (47°F). The average temperature in September is 16°C (60°F), which is lower than August's average of 19°C (66°F), and September sees a maximum temperature of 32°C (90°F), slightly less than August's peak of 35°C (96°F). Additionally, September has more rainy days (9) than August (13), leading to a total precipitation of 52 mm (2.1 in) versus August's 73 mm (2.9 in), despite a higher humidity level of 82% in September compared to 76% in August. For more specific details about August weather, you can check Aalst weather in August.

In comparing the weather patterns of September and October, we observe a notable decline in temperatures. September experiences a minimum of 4°C (40°F) and averages around 16°C (60°F), reaching a peak of 32°C (90°F). In contrast, October sees a further dip, with minimum temperatures dropping to 2°C (36°F) and an average of 13°C (55°F), while the maximum rarely surpasses 25°C (77°F). Precipitation increases from 52 mm (2.1 in) over 9 days in September to 81 mm (3.2 in) across 13 days in October, contributing to a higher humidity level of 89% compared to 82% in September. For a more detailed look at the October weather, you can refer to Aalst weather in October.

September and November showcase a stark contrast in weather patterns. In September, temperatures range from a minimum of 4°C (40°F) to a maximum of 32°C (90°F), with an average of 16°C (60°F), creating a warm and variable climate. The month sees around 52 mm (2.1 inches) of precipitation over approximately 9 days, coupled with a humidity level of 82%. In contrast, November brings cooler temperatures, with a minimum of -2°C (29°F) and a maximum of 19°C (66°F), resulting in an average of 8°C (46°F). Although the precipitation level remains similar at 53 mm (2.1 inches), it occurs over more days, totaling 12, and the humidity rises to 92%. For a more detailed look at November weather conditions, visit Aalst weather in November.

September and December weather exhibit notable differences, particularly in temperature and precipitation patterns. In September, temperatures range from a comfortable minimum of 4°C (40°F) to a warm maximum of 32°C (90°F), with an average of 16°C (60°F). The month sees a relatively low precipitation level of 52 mm (2.1 in) over about 9 days, while humidity sits at 82%. In contrast, December experiences much colder temperatures, with a minimum of -4°C (25°F), an average of 6°C (43°F), and a maximum of only 15°C (59°F). Precipitation increases significantly to 89 mm (3.5 in) over 16 days, and humidity rises slightly to 92%. For more detailed insights into the December climate, you can check Aalst weather in December.

Compare Aalst's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Aalst

As September unfolds in Aalst, the transition from summer warmth to autumn begins, marked by a considerable range in temperature. Days can still be quite warm, reaching up to 32°C, while nights usher in a cooler air with lows around 4°C. This month also experiences a notable amount of precipitation, with rain making an appearance on about 9 days, resulting in a humid atmosphere that can feel quite sultry given the average humidity of 82%. Compared to other months, September offers a unique blend of lingering warmth and the first hints of autumn’s chill, inviting residents and visitors alike to savor the beautiful, albeit changeable, weather. For more details on how these conditions shape the local climate, visit Aalst Climate.