September Weather in Heilbronn, Germany

Last updated: February 26, 2025

In September, Heilbronn, Germany, experiences a delightful mix of temperatures, with a maximum reaching 31°C (88°F) and an average of 15°C (60°F), showcasing the transition from summer's warmth to autumn's coolness. However, the month is not without its moisture, as it sees about 51 mm (2.0 in) of precipitation over 9 days, contributing to a relatively high humidity level of 85%. This blend of warm days and occasional rain creates a dynamic climate, perfect for enjoying the beauty of early fall in this charming city.

September Temperature in Heilbronn

In Heilbronn, Germany, September marks a delightful transition as summer begins to wane. With temperatures ranging from a mild 3°C (38°F) to a comfortable high of 31°C (88°F), the month offers a pleasant mix of warmth and coolness. The average temperature settles at a cozy 15°C (60°F), making it an ideal time for outdoor activities before the chill of autumn sets in. Notably, the beginning of September enjoys summer-like warmth, with the thermometer often reaching its peak. As the month progresses, a subtle coolness sets in, hinting at the approaching fall. This trend showcases September as a vibrant and inviting month, blending the late-summer sunshine with the crispness of autumn that lies just around the corner.

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

The chart illustrates September temperature patterns in Heilbronn, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec353943505766686860524238
Data source: Temperature data for Heilbronn 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 Heilbronn

In September, Heilbronn experiences a noticeable decline in precipitation, with 51 mm (2.0 in) of rain spread over just 9 days. This marks a shift from the wetter summer months, as both July and August averaged 67 mm and 65 mm respectively, accompanied by a higher frequency of rainy days. As autumn approaches, the precipitation not only decreases in volume but also becomes less frequent, representing a transition towards the drier conditions typical of the upcoming months. Interestingly, the pattern of rainfall is quite cyclical, showing that while September brings a respite from summer showers, its precipitation levels align closely with those of November, which also records 51 mm but with a higher incidence of rainy days, signaling the return of wetter weather as winter looms.

September Precipitation Trends in Heilbronn

The chart displays monthly precipitation patterns in Heilbronn, 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.
JanFebMarAprMayJunJulAugSepOctNovDec8074913785856765517552130
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Heilbronn

In Heilbronn, Germany, September ushers in a moderate shift in humidity, with levels reaching 85%. As summer fades, this month sees a slight increase compared to the preceding months, particularly August's 84%. The trend reveals a gradual ascent in humidity from the drier days of May (79%) through the summer, peaking in the winter months, where January and December both hover around 91%. Overall, September serves as a bridge between the warmth of summer and the chill of autumn, providing a refreshing yet increasingly humid backdrop for the gradual seasonal transition.

September Average Humidity in Heilbronn

This chart illustrates the average monthly humidity levels in Heilbronn, with September's data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, allowing you to see how September's humidity levels compare to other months.
JanFebMarAprMayJunJulAugSepOctNovDec91%89%87%83%79%82%83%84%86%88%89%91%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Heilbronn

As summer gives way to autumn in Heilbronn, September's UV Index reflects a notable shift, maintaining a high rating of 6 with a burn time of 25 minutes. This slight decline from the peak 8 observed during the summer months indicates a continued need for sun protection, albeit with slightly more time before skin damage occurs. The trend shows that while UV levels are lower than in July and August, vigilance remains essential, especially as outdoor activities abound. With the arrival of more moderate conditions in October, this month serves as a reminder to stay informed about changing UV levels. For more details on UV exposure and safety precautions, check out Heilbronn UV Index.

Maximum UV Index Levels in Heilbronn for September

The chart shows the monthly maximum UV Index (UVI) for Heilbronn 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.
JanFebMarAprMayJunJulAugSepOctNovDec235688876421
Data source: Heilbronn 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 Heilbronn

As September arrives in Heilbronn, Germany, it offers a delightful blend of lingering summer warmth and the anticipation of autumn. With 321 hours of sunshine, the month retains a significant portion of the vibrant light seen throughout the summer, notably less than July's dazzling peak of 412 hours, yet showcasing a commendable brightness that outshines the earlier months of the year. This gradual decline from summer’s exuberance, following August’s 383 hours, hints at the seasonal transition, while still providing ample opportunities to bask in the sun’s glow. As October approaches, bringing an expected drop to 263 hours, September stands as a beautiful capstone to the warm months, inviting residents and visitors alike to relish the last rays of summer.

Monthly Sunshine Duration in Heilbronn: September Highlighted

The September sunshine duration represents the total number of hours Heilbronn 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.
JanFebMarAprMayJunJulAugSepOctNovDec125h209h281h346h383h390h412h383h321h263h194h143h
Data source: Heilbronn September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Heilbronn During September

In Heilbronn, Germany, September stands out as a significant month for sunshine, boasting a 44% chance of sunny weather. This likelihood is on par with the spring months of March and April, indicating a notable transition from the wetter summer months where sunlight decreases to 30% in May and 31% in August. As the region moves into autumn, the sunny prospects begin to decline, with October and November seeing only 32% and 18% chances, respectively. Thus, September emerges as a perfect time to enjoy the lingering warmth of summer and the golden hues of early autumn, making it ideal for outdoor activities and exploration.

Percentage of Sunny Days in September in Heilbronn

The chart illustrates the percentage of sunny days in Heilbronn 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 Heilbronn experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec11%37%44%46%30%34%37%31%44%32%19%15%
Data source: Heilbronn September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Heilbronn in September

As summer fades into autumn in Heilbronn, Germany, September marks a significant transition with approximately 12 hours of daylight. This reduction follows the peak of 16 hours in June, showcasing the gradual shift towards shorter days. The daylight duration reflects a captivating trend: it begins at 8 hours in January and climbs steadily through the spring months, peaking in the vibrant days of late spring and summer. Following a robust August with 14 hours, September's decrease is a gentle reminder of the changing seasons, leading us back toward the more subdued daylight hours of fall and winter, where October will bring just 10 hours. This rhythmic ebb and flow of daylight not only shapes our daily routines but also enriches the natural beauty of the region throughout the year.

Average Daylight Hours in Heilbronn for September

The chart illustrates the variation in daylight duration in Heilbronn throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec8h 42m10h 8m11h 55m13h 45m15h 20m16h 9m15h 43m14h 18m12h 32m10h 43m9h 6m8h 14m
Data source: Heilbronn daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Heilbronn

As September unfurls its crisp spirit in Heilbronn, the average wind speed drops to a gentle 2.0 m/s (4 mph), marking a noticeable decline from the more invigorating breezes of summer. This softening wind heralds the transition into autumn, contrasting sharply with May's peak gusts of 3.5 m/s (8 mph). Throughout the year, it becomes evident that winter and early spring months enjoy slightly breezier conditions, such as January with 3.4 m/s (8 mph). Yet, as the seasons shift, September’s calm winds invite a reflective pause, allowing residents and visitors alike to fully embrace the beauty of changing leaves and cooler days. The trend clearly signifies that while the winds may whisper in September, they also foretell the cozy encounters of autumn that lie ahead.

Average September Wind Speed in Heilbronn

The chart displays monthly wind speed patterns in Heilbronn, 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.
JanFebMarAprMayJunJulAugSepOctNovDec3.42.92.92.63.52.12.32.62.0 m/s2.62.42.9
Data source: Heilbronn September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Heilbronn Compares to Other Months

The weather in Heilbronn changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of September's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in Heilbronn and find detailed weather information for every month.

In comparing the weather between September and January, one can observe a stark contrast in temperature and conditions. September boasts a wide temperature range, with minimums around 3°C (38°F) and maximums soaring up to 31°C (88°F), while averaging a comfortable 15°C (60°F). The month experiences 51 mm of precipitation over approximately 9 days, accompanied by humidity levels of 85%. In comparison, January is markedly colder, with temperatures dipping to a minimum of -13°C (8°F) and only reaching a maximum of 13°C (55°F), averaging just 2°C (35°F). This chillier month sees increased precipitation of 80 mm spread across 12 days and slightly higher humidity at 91%. For more detailed information, visit Heilbronn weather in January.

September and February present contrasting weather patterns, showcasing the shift from late summer to winter. In September, temperatures range from a minimum of 3°C (38°F) to a maximum of 31°C (88°F), with an average of 15°C (60°F), accompanied by a relatively lower precipitation of 51 mm (2.0 in) over 9 days, and humidity at 85%. In stark contrast, February experiences much colder temperatures, with a minimum of -12°C (12°F) and a maximum of 19°C (66°F), yielding an average of 4°C (39°F). Precipitation increases to 74 mm (2.9 in) over 11 days, and humidity rises slightly to 89%. For a detailed look at February's weather, you can visit Heilbronn weather in February.

In comparing the weather between September and March, we see distinct differences. September typically enjoys milder temperatures with a minimum of 3°C (38°F) and an average of 15°C (60°F), reaching highs of 31°C (88°F). In contrast, March experiences colder conditions, with temperatures dipping as low as -11°C (13°F) and averaging around 6°C (43°F), peaking at 22°C (72°F). Both months experience significant rainfall, with March receiving 91 mm (3.6 in) over 14 days, compared to September's 51 mm (2.0 in) over 9 days. Humidity is relatively high in both months, with September at 85% and March slightly higher at 87%. For more information on March weather specifics, you can visit Heilbronn weather in March.

When comparing the weather in September and April, we can observe notable differences in temperature and precipitation. September generally features milder temperatures, with a minimum of 3°C (38°F), an average of 15°C (60°F), and a maximum of 31°C (88°F), while April starts cooler, with a minimum of -4°C (26°F) and an average of 10°C (50°F), peaking at 27°C (80°F). Both months receive similar levels of precipitation, with September receiving 51 mm (2.0 in) and April 37 mm (1.5 in), each experiencing about 9 days of rainfall. Humidity levels are also quite close, with September at 85% and April at 83%. For more detailed insights on April weather, you can check Heilbronn weather in April.

When comparing the weather in September and May, notable differences in temperature and precipitation patterns emerge. September generally experiences a wider temperature range, with minimums as low as 3°C (38°F) and maximums reaching up to 31°C (88°F). In contrast, May sees slightly cooler temperatures, with minimums dropping to -1°C (30°F) and maximums capping at 30°C (87°F). Additionally, September tends to be drier, with 51 mm (2.0 in) of precipitation over about 9 days, while May is rainier, accumulating 85 mm (3.3 in) over approximately 14 days. Humidity levels are higher in September at 85%, compared to May's 79%. For a more detailed look at May weather, you can visit Heilbronn weather in May.

When comparing the weather in September and June, notable differences emerge in temperature and precipitation patterns. September typically sees a broader temperature range, with minimums dipping to 3°C (38°F) and maximums reaching 31°C (88°F), while June presents a milder temperature spectrum, with minimums at 7°C (44°F) and maximums peaking at 34°C (94°F). In terms of precipitation, June is wetter, averaging 85 mm over 12 days compared to September's 51 mm over 9 days, though both months experience relatively high humidity levels, with September slightly higher at 85% versus June's 82%. For more detailed insights, you can check Heilbronn weather in June.

When comparing the weather in September and July, it's clear that July tends to be warmer overall. September experiences a wider temperature range, with minimums dropping to 3°C (38°F) and maximums reaching 31°C (88°F), averaging around 15°C (60°F). In contrast, July has a milder minimum temperature of 7°C (45°F) and can peak at 36°C (97°F), with an average of 20°C (68°F). July also sees slightly more precipitation, with 67 mm (2.6 in) over 12 days, compared to September’s 51 mm (2.0 in) over 9 days. Humidity levels remain fairly similar, at 85% in September and 83% in July. For more detailed insights, you can explore Heilbronn weather in July.

In comparing the weather conditions of September to August, September tends to be cooler, with minimum temperatures dropping to 3°C (38°F) and an average of 15°C (60°F), while August sees minimums of 6°C (43°F) and an average of 20°C (68°F). The maximum temperatures in September reach up to 31°C (88°F), whereas in August, they peak higher at 35°C (95°F). Precipitation is also a bit less in September, totaling 51 mm (2.0 in) over 9 rainy days, compared to 65 mm (2.6 in) over 13 days in August. Humidity levels remain similar, with September at 85% and August slightly lower at 84%. For a closer look at August's climate, check out Heilbronn weather in August.

September typically sees a wider range of temperatures, with a minimum of 3°C and a maximum of 31°C, resulting in an average of 15°C. In contrast, October's temperatures dip lower, featuring a minimum of -1°C and an average of 11°C, with a maximum reaching 25°C. The month of October also experiences more precipitation, totaling 75 mm over 12 days compared to September's 51 mm over 9 days, and it has a slightly higher humidity level of 88%. For those looking for more detailed information on October conditions, check out Heilbronn weather in October.

September and November exhibit notable differences in weather patterns despite having the same amount of precipitation (51 mm) and the same number of rainy days (9 days). In September, temperatures range from a minimum of 3°C (38°F) to a maximum of 31°C (88°F), with an average of 15°C (60°F), contributing to a generally warmer and more variable climate. In contrast, November experiences cooler temperatures, with a range from a minimum of -3°C (27°F) to a maximum of 21°C (71°F) and an average of only 5°C (42°F). Additionally, November has a slightly higher humidity level at 89%, compared to September's 85%, resulting in a more crisp and chilly atmosphere. For more detailed information, you can check Heilbronn weather in November.

In September, the weather is typically milder, with average temperatures hovering around 15°C (60°F) and highs reaching up to 31°C (88°F), making it a warm month with a relatively lower precipitation of 51 mm (2.0 in) over about 9 days. In contrast, December brings a significant drop in temperature, averaging just 3°C (38°F) and experiencing colder nights with minimums reaching -7°C (20°F). Additionally, December sees increased precipitation, totaling 130 mm (5.1 in) across 19 days, and a higher humidity level of 91%. For a more detailed look at December's weather, check out Heilbronn weather in December.

Compare Heilbronn's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Heilbronn

As September unfolds in Heilbronn, the weather offers a delightful transition from summer's warmth to autumn's embrace. While the month can see a peak temperature of 31°C (88°F), the average is a much cooler 15°C (60°F), showcasing a notable drop in warmth compared to the scorching summer months. The rise in humidity to around 85% can make the air feel quite different, infusing a cozy yet moist quality to the atmosphere. Rainfall is also a characteristic feature, with about 51 mm (2.0 in) accumulating over the course of 9 days, a trend that sets September apart from the drier, hotter days of July and August. For an in-depth look at the unique weather patterns throughout the year, visit Heilbronn Climate.