Last updated: February 24, 2025
September in Porto, Portugal offers a delightful blend of warm temperatures and refreshing coastal breezes. With maximums reaching up to 34°C (94°F) and an inviting average of 20°C (68°F), it's the perfect month for outdoor exploration. Although temperatures can dip to a cool 10°C (51°F) at night, the warmth during the day encourages visitors to enjoy the city's vibrant atmosphere. Rainfall is minimal, with a total of 39 mm (1.5 in) spread over just 6 days, ensuring plenty of sunshine for sightseeing. Coupled with a humidity level of 71%, the weather serves as a pleasant backdrop for experiencing Porto's rich culture and stunning landscapes.
In September, Porto experiences a delightful transition as summer begins to wane, bringing with it some of the year's warmest temperatures. The minimum temperature settles around 10°C (51°F), while the average hovers at a comfortable 20°C (68°F), making it an inviting time to explore the city. As daylight hours shorten, the maximum temperature still reaches a pleasant 34°C (94°F) on warmer days, allowing for outdoor activities against a backdrop of stunning autumn colors. This month captures the essence of late summer in Porto, where the warm days encourage lively street life and the evenings provide a chance to savor local wines by the river.
In September, Porto, Portugal begins to feel the shift towards autumn, with precipitation amounting to 39 mm (1.5 in) over an average of 6 rainy days. This marks a noticeable increase compared to the drier summer months of July and August, which saw only 23 mm (0.9 in) and 19 mm (0.7 in) of rain, respectively. As the month progresses, the likelihood of showers begins to rise, paving the way for the wetter months ahead, where October averages 121 mm (4.8 in) of rain. This gradual transition underscores a return to moderate rainfall, characteristic of Porto's climate, as it moves from the dry heat of summer into the more temperate and wet autumn season.
In September, Porto experiences a notable shift in humidity levels, settling at 71%. This change marks a brief reprieve from the warm summer months, where humidity peaks at 64% in August. As autumn approaches, the air becomes slightly thicker, foreshadowing the wetter months ahead. Overall, the trend reveals an interesting pattern: humidity levels tend to rise throughout the year, with the highest readings during the winter months, reaching a peak of 87% in both January and December. This cyclical nature of humidity in Porto underscores the city's transition from the drier, sun-soaked summers to the lush, moisture-laden winters, providing a unique climate backdrop for both residents and visitors alike.
As summer transitions to autumn in September, Porto, Portugal, experiences a very high UV Index of 8, indicating that sun exposure requires caution. The burn time for unprotected skin is around 15 minutes, reflective of the lingering intensity from the peak summer months. This trend highlights a gradual decline in UV levels as the year progresses, dropping from a scorching 11 in June to 8 in September, reinforcing the importance of sun protection. With the high UV levels still dominant, it's crucial for residents and visitors alike to remain vigilant. For more detailed information, check out the Porto UV Index.
UV Risk Categories
As summer gracefully transitions into autumn, September in Porto, Portugal continues to bask in the warmth of sun-kissed days, offering an impressive 346 hours of sunshine. This vibrant month captures the tail end of the sunny season, with daylight hours still abundant, albeit a slight decrease from the peak of 427 hours in July. As the city begins to cool, the radiant sunshine of September provides a lush backdrop for exploring Porto's picturesque streets and tasting its renowned cuisine. The trends clearly show a gentle descent from the height of summer, yet September maintains a pleasant brightness that invites both locals and visitors to enjoy the lingering warmth before autumn fully settles in.
As summer transitions to autumn, September in Porto offers a varied weather experience with a 42% chance of sunny days. This figure reflects a dip from the previous months, highlighting a shift as the vibrant August sun with its 64% chance gives way to cloudier skies. Notably, June and July also enjoyed higher probabilities of sunshine, at 55% and 57% respectively, suggesting that while September may still boast pleasant weather, it doesn't quite reach the heights of mid-summer. As the month unfolds, visitors can anticipate a balance of sun and cloud, perfect for exploring Porto's charming streets while still savoring those warm rays characteristic of late summer days.
As summer fades, September in Porto, Portugal, offers a gentle transition with 12 hours of daylight. This marks a soft decrease from the peak of 15 hours in June, reflecting the city's gradual shift from long sunny days to the crisper ambiance of autumn. The daylight duration steadily declines as months progress, with October bringing a further reduction to 11 hours. Despite the diminishing light, September retains a vibrant charm, allowing visitors and locals alike to relish in the lingering warmth and extended twilight, making it an ideal time for outdoor activities while the days are still long enough to savor.
In September, Porto experiences a gentle breeze with an average wind speed of 2.8 m/s (6 mph), maintaining a calm yet refreshing atmosphere as summer transitions into autumn. This slight increase from August's 2.7 m/s signals the start of a gradual uptick in wind as the year progresses, moving towards the more blustery months ahead. It's a time when the coastal city's iconic views are complemented by the soft rustling of leaves, providing a picturesque backdrop for leisurely strolls along the Douro River. As the wind gently whispers through the streets, visitors can enjoy the serene blend of warmth and coolness, making September a delightful month for exploration and discovery in Porto.
The weather in Porto 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 Porto and find detailed weather information for every month.
September and January present distinctly different weather patterns. In September, temperatures range from a mild 10°C (51°F) at night to a warm 34°C (94°F) during the day, with an average of 20°C (68°F). This month sees relatively low precipitation, totaling 39 mm (1.5 in) over about 6 days, and a humidity level of 71%. In contrast, January features much cooler temperatures, with nighttime lows dropping to 0°C (32°F) and daytime highs peaking at 21°C (69°F), averaging around 9°C (49°F). Additionally, January is wetter, receiving 91 mm (3.6 in) of rainfall over 8 days, with a higher humidity level of 87%. For more detailed insights on January weather, you can visit Porto weather in January.
Comparing the weather in September and February reveals notable differences. September boasts a more diverse temperature range, with minimums around 10°C (51°F) and maximums reaching up to 34°C (94°F), making it generally warmer with an average of 20°C (68°F). In contrast, February experiences cooler temperatures, ranging from a chilly minimum of 1°C (34°F) to a maximum of 21°C (71°F) and an average of 11°C (52°F). Precipitation also differs significantly; September receives 39 mm (1.5 in) over about 6 days, while February sees much higher rainfall of 138 mm (5.4 in) across 11 days. Additionally, February tends to have higher humidity at 81%, compared to September's 71%. For a closer look at February weather, you can check out Porto weather in February.
September and March present contrasting weather patterns. In September, temperatures range from a mild 10°C (51°F) to a warm 34°C (94°F), with an average of around 20°C (68°F). The month sees relatively low precipitation at 39 mm (1.5 in) over 6 days, coupled with a humidity level of 71%. Conversely, March is cooler, with temperatures ranging from a minimum of 3°C (38°F) to a maximum of 26°C (79°F), averaging at 12°C (54°F). It experiences significantly higher precipitation totaling 141 mm (5.6 in) across 11 days and a humidity level of 78%. For more details on the weather conditions during this month, you can refer to Porto weather in March.
September and April present contrasting weather patterns. In September, temperatures range from a minimum of 10°C (51°F) to a maximum of 34°C (94°F), with an average of 20°C (68°F), making it warmer overall. In contrast, April enjoys milder temperatures, with minimums at 4°C (40°F) and maximums reaching 27°C (81°F), averaging 14°C (58°F). However, April is notably wetter, receiving 146 mm (5.7 in) of precipitation over 13 days, compared to September’s 39 mm (1.5 in) across just 6 days. Additionally, humidity levels are slightly higher in April at 79%, compared to 71% in September. For more detailed insights, check Porto weather in April.
September generally offers warmer temperatures compared to May, with averages peaking at 20°C (68°F) and maximums reaching up to 34°C (94°F). In contrast, May has a cooler average of 17°C (63°F) and maximums of 30°C (87°F). However, May tends to experience more rainfall, with 81 mm (3.2 in) over 9 days, while September sees less precipitation at 39 mm (1.5 in) across 6 days. Additionally, humidity levels are slightly higher in May at 78% compared to September's 71%. For a more detailed look at May weather, visit Porto weather in May.
When comparing the weather in September and June, both months exhibit mild temperatures with minimums around 10°C (50-10°C) and maximums reaching into the low 30s°C. September tends to be slightly warmer, averaging 20°C (68°F) compared to June's average of 18°C (66°F). Precipitation is relatively similar, with September receiving 39 mm (1.5 in) over 6 days and June experiencing a bit more rain at 50 mm (2.0 in) across 8 days. Interestingly, humidity levels remain constant at 71% in both months, contributing to a comfortable yet somewhat humid atmosphere. For more detailed insights regarding the climate, you can check Porto weather in June.
September and July in Porto share similar maximum temperatures, both reaching highs of 34°C (94°F). However, September presents a slightly cooler average temperature of 20°C (68°F) compared to July's 21°C (70°F). In terms of precipitation, September tends to be wetter, receiving 39 mm (1.5 in) over 6 days, while July is drier with only 23 mm (0.9 in) across 4 days. Additionally, September has a higher humidity level at 71%, as opposed to July's 63%. For more detailed information on July's weather, you can visit Porto weather in July.
In comparing the weather between August and September, we see a noticeable shift in temperature and precipitation patterns. In August, the minimum temperature is slightly higher at 12°C (54°F), with an average of 21°C (70°F) and a peak of 36°C (98°F), suggesting hot summer days. The month also sees less precipitation, totaling 19 mm (0.7 in) over just 4 days, accompanied by lower humidity at 64%. In contrast, September experiences a drop in minimum temperature to 10°C (51°F) and an average of 20°C (68°F), with a maximum of 34°C (94°F). This month has increased precipitation of 39 mm (1.5 in) spread over 6 days, and humidity rises to 71%. Overall, September offers a more varied climate, while August maintains the heat of summer. For additional details, visit Porto weather in August.
September typically enjoys milder weather, with temperatures ranging from a minimum of 10°C (51°F) to a maximum of 34°C (94°F) and an average of 20°C (68°F). Rainfall is relatively low, with only 39 mm (1.5 in) over about 6 days, and humidity averaging 71%. In contrast, October sees a notable drop in temperatures, ranging from a minimum of 6°C (44°F) to a maximum of 31°C (88°F) and an average of 17°C (62°F). Precipitation increases significantly to 121 mm (4.8 in), occurring over 10 days, and humidity rises to 79%. For more detailed information, check out Porto weather in October.
September weather typically showcases a significant range in temperatures, with minimums around 10°C (51°F) and summer-like highs reaching up to 34°C (94°F). The month averages a comfortable 20°C (68°F) but experiences relatively low precipitation, totaling 39 mm (1.5 in) over about 6 days, and maintains a moderate humidity level of 71%.
In contrast, November brings much cooler weather, with minimum temperatures dropping to 4°C (40°F) and an average of only 13°C (55°F). The maximum temperature in November peaks at 21°C (71°F), but the month is considerably wetter, accumulating 156 mm (6.1 in) of rain over 13 days, along with higher humidity at 86%. For more detailed insights, check out Porto weather in November.
September and December weather in Porto reveal striking contrasts. In September, temperatures range from a mild 10°C (51°F) at night to a warm 34°C (94°F) during the day, with an average of 20°C (68°F). Precipitation is relatively low at 39 mm (1.5 in) over approximately six days, and humidity is moderate at 71%. In contrast, December brings significantly cooler temperatures, with a minimum of 1°C (35°F) and a maximum of 18°C (65°F), averaging just 11°C (52°F). The month sees a dramatic increase in precipitation to 187 mm (7.4 in) spread across about 15 days, and humidity rises to a higher 87%. For more detailed insights, check Porto weather in December.
As summer transitions to autumn, September in Porto presents a unique climatic character. The warm days can still reach high temperatures, making it ideal for those who enjoy a bit of heat before the cooler months set in. However, the average temperature begins to decline, offering a pleasant balance for outdoor activities. With relatively low precipitation and only a handful of rainy days, visitors can still enjoy exploring the city's beauty, albeit with a hint of humidity that adds to the coastal charm. For a more detailed exploration of the weather patterns throughout the year, check out Porto Climate.