September Weather in Cascais, Portugal

Last updated: February 24, 2025

In Cascais, Portugal, September welcomes a pleasant blend of mild temperatures and moderate humidity, creating an inviting atmosphere for visitors. The average temperature hovers around 18°C (65°F), with daily highs reaching up to 23°C (74°F), ensuring comfortable days under the sun. As summer transitions to autumn, nights can cool down to a refreshing 15°C (60°F). Rain is minimal, with only 32 mm (1.2 in) of precipitation expected over just two days this month, making it ideal for outdoor activities. With humidity levels at a comfortable 67%, September proves to be a delightful time to explore the coastal beauty and charm of Cascais.

September Temperature in Cascais

In September, Cascais enjoys a delightful transition from summer to autumn, marked by mild temperatures that create a perfect Mediterranean ambiance. With a minimum of 15°C (60°F) and highs reaching 23°C (74°F), the average settles comfortably at 18°C (65°F). This month represents a subtle decline in heat compared to the sweltering summer days of August, yet it retains a warmth that encourages outdoor exploration. The weather is ideal for leisurely walks along the coastline or soaking up the sun at local beaches, making September one of the most inviting times to experience the charm of this picturesque Portuguese town. As autumn approaches, the pleasant climate invites both locals and visitors to savor the beauty of Cascais before the cooler months set in.

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

The chart illustrates September temperature patterns in Cascais, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec555657586163646465646058
Data source: Temperature data for Cascais 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 Cascais

In September, Cascais experiences a moderate precipitation level of 32 mm (1.2 in), marking a slight uptick from the arid summer months of July and August, which both received negligible rainfall. Characterized by just 2 precipitation days, this month transitions from the sun-soaked days of summer to the wetter autumn season, providing a gentle prelude to the heavier rains that typically follow in October and November. The consistency of rainfall during September suggests a gradual shift in climate, paving the way for the lush greenery that the region is known for, as the average rainfall begins to trend upward towards the year's end.

September Precipitation Trends in Cascais

The chart displays monthly precipitation patterns in Cascais, 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.
JanFebMarAprMayJunJulAugSepOctNovDec4259647133123432538973
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Cascais

In September, Cascais, Portugal experiences a notable shift in humidity levels, with an average of 67%. As summer draws to a close, the humidity begins to rise slightly from the low levels of 60% seen in July and August. This gradual increase signals the transition into autumn, as the weather becomes more temperate. The month of September acts as a bridge, blending the dry warmth of summer with the more humid conditions that will characterize the fall months ahead. Following this pattern, humidity will continue to rise reaching 74% in October before climbing back to a peak in winter with 83% in November. This dynamic shift highlights the region's distinctive seasonal changes, making Cascais a fascinating destination year-round.

September Average Humidity in Cascais

This chart illustrates the average monthly humidity levels in Cascais, 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.
JanFebMarAprMayJunJulAugSepOctNovDec85%75%72%70%70%63%60%60%68%74%83%85%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Cascais

In September, Cascais, Portugal, experiences a noteworthy UV Index of 8, falling within the very high exposure category. As summer transitions to autumn, sun-seekers still need to be cautious, with a burn time of just 15 minutes. This month marks a slight decrease from August’s peak intensity of 9, but it remains essential to protect your skin. The UV levels have shown a consistent trend of rising from a moderate 3 in January to their pinnacle at 11 in June, with September continuing the trend of heightened awareness typical of the late summer months. For practical tips on how to stay safe under the sun, visit Cascais UV Index.

Maximum UV Index Levels in Cascais for September

The chart shows the monthly maximum UV Index (UVI) for Cascais 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.
JanFebMarAprMayJunJulAugSepOctNovDec356910111098643
Data source: Cascais 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 Cascais

As summer gracefully transitions into autumn, September in Cascais continues to bask in a generous 348 hours of sunshine, making it one of the sunniest months of the year. Following the peak in July with 420 hours, the sunlight gradually dips, yet September still offers a vibrant glow, lingering beautifully on the shores and streets of this picturesque coastal town. The slight decrease from August's 395 hours suggests a gentle shift, reminding us of the upcoming cooler months, while still allowing plenty of time to enjoy outdoor activities and stunning sunsets. Overall, this trend reflects a robust summer that cascades into a warm and inviting early fall, perfect for those seeking to savor the last rays of sunshine.

Monthly Sunshine Duration in Cascais: September Highlighted

The September sunshine duration represents the total number of hours Cascais 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.
JanFebMarAprMayJunJulAugSepOctNovDec183h231h307h351h405h409h420h395h348h313h236h224h
Data source: Cascais September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Cascais During September

In Cascais, Portugal, September maintains a promising 66% chance of sunny weather, aligning closely with the peak summer months of July (69%) and August (66%). This trend reflects a consistent pattern of pleasant conditions as summer transitions into autumn, making it an ideal time for outdoor activities. Although the percentage dips in the subsequent months, with October seeing a 55% likelihood of sunshine, September still stands out as a vibrant time to enjoy the warm climate and beautiful coastal landscapes. Whether you're exploring the scenic coastline or indulging in local cuisine, September offers a delightful blend of lingering summer warmth and the allure of early autumn.

Percentage of Sunny Days in September in Cascais

The chart illustrates the percentage of sunny days in Cascais 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 Cascais experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec45%24%60%41%57%65%69%66%66%55%65%39%
Data source: Cascais September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Cascais in September

As summer gently fades in Cascais, Portugal, September offers a delightful transition into autumn with an inviting 12 hours of daylight. This month marks a gradual decrease from the peak summer hours of 14 in June through August, hinting at the approaching seasonal change. While September still bathes the city in ample sunshine, it reflects the trend of diminishing daylight that begins in late summer and continues into the fall, with October and November dropping to 11 and 10 hours, respectively. This rhythmic dance of light not only showcases the beauty of the changing seasons but also invites residents and visitors alike to savor the last warm days before winter sets in.

Average Daylight Hours in Cascais for September

The chart illustrates the variation in daylight duration in Cascais throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 46m10h 44m11h 58m13h 14m14h 17m14h 49m14h 32m13h 36m12h 23m11h 8m10h 2m9h 28m
Data source: Cascais daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Cascais

As summer fades into autumn, September in Cascais, Portugal, presents a gentle shift in the air with an average wind speed of 5.4 m/s (12 mph). This marks one of the calmer months of the year, a contrast to the preceding summer, where winds frequently peaked around 7.2 m/s (16 mph). The breezy days of May and June, with similar wind speeds, suggest a vibrant coastal energy that begins to mellow as September rolls in. With each passing month, wind speeds gradually decline, reaching their annual low in October at 5.1 m/s (11 mph). This trend of diminishing winds highlights the transition into the cooler months, inviting a more serene atmosphere, perfect for leisurely strolls along Cascais' picturesque shores.

Average September Wind Speed in Cascais

The chart displays monthly wind speed patterns in Cascais, 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.
JanFebMarAprMayJunJulAugSepOctNovDec6.96.96.04.97.37.37.26.45.4 m/s5.16.56.7
Data source: Cascais September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Cascais Compares to Other Months

The weather in Cascais 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 Cascais and find detailed weather information for every month.

In September, the weather tends to be milder and more pleasant, with average temperatures ranging from a minimum of 15°C (60°F) to a maximum of 23°C (74°F). The month sees relatively low precipitation of about 32 mm (1.2 in) over just 2 days, and humidity levels are manageable at 67%. In contrast, January experiences cooler temperatures, with an average low of 7°C (45°F) and a high of 18°C (64°F). This month is also wetter, receiving approximately 42 mm (1.7 in) of rain spread over 7 days, along with higher humidity levels at 85%. For more detailed information, check Cascais weather in January.

In September, temperatures tend to be milder, with a minimum of 15°C (60°F), an average of 18°C (65°F), and a maximum of 23°C (74°F). This month typically sees less precipitation, averaging only 32 mm (1.2 in) over about 2 days, and humidity levels are around 67%. In contrast, February experiences cooler weather, with a minimum temperature of 9°C (48°F), an average of 13°C (56°F), and a maximum of 17°C (63°F). Additionally, February is wetter, accumulating about 59 mm (2.3 in) of rain over approximately 8 days, and has higher humidity at 75%. For more details on February weather, you can visit Cascais weather in February.

In comparing September and March weather, September typically enjoys milder temperatures, with a minimum of 15°C (60°F) and an average of 18°C (65°F), peaking at 23°C (74°F). The month sees relatively low precipitation, only about 32 mm (1.2 in) over just 2 days, and maintains a comfortable humidity level of 67%. In contrast, March is cooler, with minimum temperatures dropping to 9°C (49°F) and an average of 14°C (57°F), with a maximum of 19°C (66°F). However, March experiences more rainfall, totaling 64 mm (2.5 in) across 8 days, alongside a slightly higher humidity at 72%. If you want more details about March weather specifically, you can refer to this link: Cascais weather in March.

In September, the weather tends to be milder, with average temperatures ranging from a minimum of 15°C (60°F) to a maximum of 23°C (74°F), and only about 32 mm (1.2 in) of precipitation over just two days. This results in a comfortable humidity level of 67%. In contrast, April experiences cooler temperatures, with a minimum of 10°C (50°F) and a maximum of 21°C (71°F), while precipitation is significantly higher at 71 mm (2.8 in) spread over 11 days, leading to a slightly higher humidity of 70%. For more detailed information, you can visit Cascais weather in April.

When comparing the weather in September to that of May, we can observe some notable differences. In September, temperatures range from a minimum of 15°C (60°F) to a maximum of 23°C (74°F), with an average of 18°C (65°F), while May experiences slightly cooler conditions, with temperatures ranging from 11°C (53°F) to a maximum of 24°C (76°F) and an average of 16°C (61°F). Precipitation levels are relatively similar, with September receiving 32 mm (1.2 in) over 2 days, and May experiencing 33 mm (1.3 in) over 3 days. Humidity in September stands at 67%, while May sees a slightly higher average of 70%. For a more detailed look at the weather in May, check out Cascais weather in May.

In September, the weather tends to be slightly warmer than in June, with average temperatures around 18°C (65°F) compared to June's 17°C (63°F). The maximum temperature in September can reach up to 23°C (74°F), while June peaks at 22°C (72°F). Interestingly, both months experience similar rainfall, with September having 32 mm (1.2 in) compared to June's 12 mm (0.5 in), but both only receive precipitation on about two days. Additionally, September has a higher humidity level at 67% versus June’s 63%. For those looking for specifics on June weather, you can check out Cascais weather in June.

In comparing the weather between September and July, we find some interesting variations. September experiences a slightly broader temperature range, with minimums around 15°C and maximums reaching 23°C, while July maintains a minimum of 16°C and a maximum of 21°C. Although the average temperature is similar for both months, September is generally a bit warmer, with higher humidity levels at 67% compared to July's 60%. Additionally, September sees more precipitation, averaging 32 mm over 2 days, unlike July, which enjoys only 3 mm and is typically dry with no days of rain. For more specifics on July weather, you can check Cascais weather in July.

September weather features similar average temperatures to August, with both months experiencing an average of 18°C (65°F) and maximum temperatures reaching up to 23°C (74°F). However, September tends to be slightly cooler, with a minimum temperature of 15°C (60°F), compared to August's minimum of 16°C (61°F). In terms of precipitation, September sees an increase with 32 mm (1.2 in) over 2 days, while August remains quite dry, receiving only 4 mm (0.1 in) across a single day. Additionally, September has a higher humidity level at 67%, compared to August's 60%, making it feel a bit more muggy. For more detailed weather insights, you can explore Cascais weather in August.

September and October present a noticeable shift in weather patterns. While September boasts a milder climate with average temperatures around 18°C (65°F) and only two days of rain, October sees a slight drop in minimum temperatures to 11°C (52°F) and an increase in precipitation to 53 mm (2.1 in) over six days. Humidity also rises in October, reaching 74% compared to September's 67%. Despite these changes, both months share the same maximum temperature of 23°C (74°F). For more detailed insights, you can check Cascais weather in October.

In September, temperatures are generally milder, with a minimum of 15°C (60°F) and an average of 18°C (65°F), peaking at a comfortable 23°C (74°F). The month sees relatively low precipitation, with only 32 mm (1.2 in) falling over just 2 days, and humidity levels at around 67%. In contrast, November experiences cooler temperatures, with a minimum of 11°C (53°F) and an average of 16°C (60°F), reaching a maximum of 20°C (68°F). However, it is significantly wetter, with 89 mm (3.5 in) of rain spread over 11 days, leading to higher humidity levels at 83%. For more details on the weather in November, you can visit Cascais weather in November.

In September, the weather is relatively mild with temperatures ranging from a minimum of 15°C (60°F) to a maximum of 23°C (74°F) and an average of 18°C (65°F). Precipitation is minimal, averaging 32 mm (1.2 in) over just 2 days, accompanied by a humidity level of 67%. In contrast, December sees cooler temperatures, with a minimum of 9°C (49°F), an average of 14°C (58°F), and a maximum of 17°C (63°F). This month experiences significantly more rainfall, totaling 73 mm (2.9 in) over 10 days, and higher humidity levels at 85%. For more details on December weather, visit Cascais weather in December.

Compare Cascais's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Cascais

As summer transitions to autumn, September in Cascais offers a pleasant reprieve from the heat, with comfortable temperatures averaging around 18°C (65°F) and maximum days peaking at a warm 23°C (74°F). This month stands out with its relatively low precipitation, seeing just a couple of rainy days, making it ideal for enjoying outdoor activities. The humidity levels remain moderate, striking a balance between warmth and cool ocean breezes. Overall, September serves as a sweet spot in the seasonal shift, gracefully blending the lingering warmth of summer with the crispness of fall. For more detailed information on the weather patterns throughout the year, check Cascais Climate.