September Weather in Llanberis, United Kingdom

Last updated: March 17, 2025

In September, Llanberis, United Kingdom, experiences a mild climate characterized by a maximum temperature of 26°C (78°F) and an average of 14°C (57°F), ideal for exploring the stunning landscapes. However, the weather can be unpredictable, with minimum temperatures dropping to 6°C (42°F). This month typically sees 146 mm (5.7 in) of rainfall spread over 18 days, resulting in a humidity level of 85%, which contributes to the lush greenery of the region. Visitors should be prepared for a mix of sunshine and showers while enjoying the breathtaking scenery this charming village has to offer.

September Temperature in Llanberis

September in Llanberis welcomes a refreshing transition towards autumn, characterized by mild temperatures that range from a minimum of 6°C (42°F) to a pleasant maximum of 26°C (78°F). With an average of 14°C (57°F), the days are often sunny and ideal for exploring the stunning landscapes of this picturesque locale. As the month progresses, visitors can expect the last whispers of summer warmth, making it an excellent time for outdoor activities. Compared to the preceding summer months, September shows a gentle decline in temperatures while still offering a comfortable climate for hiking and sightseeing, embodying the tranquil beauty of early autumn in the heart of Wales.

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

The chart illustrates September temperature patterns in Llanberis, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec424344475257605957524744
Data source: Temperature data for Llanberis 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 Llanberis

In September, Llanberis experiences a significant 146 mm (5.7 in) of precipitation, marking a notable transition as summer fades and autumn approaches. This monthly total reflects a consistent pattern of dampness, as September greets the region with a moderate 18 rainy days—a continuation of the wetter conditions established in August. While not as drenched as October's anticipated deluge of 206 mm (8.1 in), September's rainfall is crucial for replenishing the lush landscapes that Llanberis is renowned for. As the dry spells of spring and early summer fade further into memory, residents and visitors alike can expect the characteristic charm of the Welsh countryside, wrapped in a blanket of autumn colors and welcomed by gentle rains.

September Precipitation Trends in Llanberis

The chart displays monthly precipitation patterns in Llanberis, 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.
JanFebMarAprMayJunJulAugSepOctNovDec1211621526287106105162146206176203
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Llanberis

In Llanberis, September marks a noticeable uptick in humidity, settling at 85%—a modest rise from the summer months. This increase signals the transition towards autumn as the air begins to feel a bit heavier, especially compared to the drier conditions experienced in July and August at 78% and 79%, respectively. Following September, the humidity continues to climb, peaking at 90% in October and reaching 91% in November. Overall, these trends illustrate Llanberis' characteristic shift from the warmth of summer to the cooler, more moisture-laden air of autumn, encapsulating the region's enchanting climate and its vibrant seasonal changes.

September Average Humidity in Llanberis

This chart illustrates the average monthly humidity levels in Llanberis, 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.
JanFebMarAprMayJunJulAugSepOctNovDec89%88%86%85%79%81%78%79%85%90%91%89%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Llanberis

As summer transitions into autumn, September in Llanberis, United Kingdom, sees a UV Index of 5, placing it in the moderate exposure category. This marks a notable decrease from the very high levels experienced in June and July, where the UV Index peaked at 8, necessitating careful sun protection. With a burn time of about 30 minutes, residents and visitors are reminded to balance their outdoor activities while still enjoying the lingering warmth of early fall. This gradual dip reflects a trend towards lower UV exposure as the months progress, providing a timely reminder to be sun-smart as the daylight hours shorten. For more detailed information about UV levels throughout the year, visit Llanberis UV Index.

Maximum UV Index Levels in Llanberis for September

The chart shows the monthly maximum UV Index (UVI) for Llanberis 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.
JanFebMarAprMayJunJulAugSepOctNovDec124578875421
Data source: Llanberis 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 Llanberis

As summer wanes, September in Llanberis graces residents and visitors with a delightful 315 hours of sunshine, making it one of the sunniest months of the transition into autumn. Following the peak brightness of July, which boasted an impressive 421 hours, September still holds its own, allowing for pleasant outdoor activities against the stunning backdrop of mountains and lakes. This steady decline in sunshine hours signals the seasonal shift, yet it contrasts the sharp drop ahead in the colder months of October and November, where sunlight plummets to 238 and 126 hours, respectively. The lingering warmth and light of early autumn make September a perfect time for exploring the natural beauty of this charming corner of the UK.

Monthly Sunshine Duration in Llanberis: September Highlighted

The September sunshine duration represents the total number of hours Llanberis 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.
JanFebMarAprMayJunJulAugSepOctNovDec93h162h228h335h415h404h421h383h315h238h126h109h
Data source: Llanberis September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Llanberis During September

In Llanberis, September experiences a modest 22% chance of sunny weather, marking a slight decline from the summer months. As the transition from summer to autumn occurs, sunshine becomes less frequent, similar to the trends observed in July and August, where sunny days peaked at 36% and 25%, respectively. This gradual decrease is typical for the region, with October bringing even dimmer prospects at 15%. However, with April's impressive 46% sunshine potential, September's weather is not without its charms, inviting visitors to enjoy the picturesque landscapes of the Snowdonia National Park—even if they might want to keep an umbrella handy!

Percentage of Sunny Days in September in Llanberis

The chart illustrates the percentage of sunny days in Llanberis 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 Llanberis experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec20%22%25%46%30%27%36%25%22%16%20%20%
Data source: Llanberis September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Llanberis in September

In Llanberis, United Kingdom, the progression of daylight duration throughout the year paints a vivid picture of the changing seasons. September marks a gentle transition from the long, sunlit days of summer—where daylight stretched to a generous 16 hours in June and July—to the shorter, cozy evenings of autumn. With 12 hours of daylight this month, the days begin to wane, offering a softer glow as nature prepares for the cooler months ahead. Following the vibrant backdrop of August's 14 hours, September serves as a reminder of the ebbing sunlight, setting the stage for October's further reduction to 10 hours. This gradual shift not only influences the landscape but also the rhythms of daily life, inviting residents and visitors alike to embrace the charm of autumn's arrival.

Average Daylight Hours in Llanberis for September

The chart illustrates the variation in daylight duration in Llanberis throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec8h 10m9h 51m11h 54m14h15h 51m16h 50m16h 18m14h 38m12h 36m10h 31m8h 38m7h 37m
Data source: Llanberis daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Llanberis

As summer yields to autumn in Llanberis, September brings a gentle breeze with an average wind speed of 3.7 m/s (8 mph), creating a serene atmosphere perfect for outdoor exploration. This mild wind speed is consistent with the trend of gradually decreasing winds throughout the summer months, peaking in February at 6.6 m/s (15 mph) before the calmer days of July and August. Interestingly, September's winds are slightly stronger than those in July and August, hinting at the subtle transition toward the brisker days of autumn. As the month progresses, expect the wind to pick up again in October, setting the stage for the cooler, invigorating air that characterizes the later fall months.

Average September Wind Speed in Llanberis

The chart displays monthly wind speed patterns in Llanberis, 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.
JanFebMarAprMayJunJulAugSepOctNovDec5.36.65.73.84.74.03.24.43.7 m/s6.45.55.9
Data source: Llanberis September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Llanberis Compares to Other Months

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

In September, the weather is generally warmer, with temperatures ranging from a minimum of 6°C (42°F) to a maximum of 26°C (78°F), and an average temperature of 14°C (57°F). This month sees significant rainfall, with 146 mm (5.7 in) spread over 18 days and a humidity level of 85%. In contrast, January brings much cooler temperatures, with a minimum of -1°C (30°F) and a maximum of 13°C (55°F), averaging around 6°C (43°F). Although precipitation is slightly lower at 121 mm (4.8 in) over 16 days, the humidity remains high at 89%. For a closer look at January conditions specifically, you can visit Llanberis weather in January.

In comparing the weather of September and February, September tends to be milder with temperatures ranging from a minimum of 6°C (42°F) to a maximum of 26°C (78°F), while February is much cooler, with temperatures dipping as low as -3°C (28°F) and capping at 15°C (60°F). September experiences an average temperature of 14°C (57°F) and only 146 mm (5.7 in) of precipitation over 18 days, whereas February sees slightly higher precipitation at 162 mm (6.4 in) across 19 days, coupled with higher humidity levels at 88%. For more information, check out Llanberis weather in February.

September and March present contrasting weather patterns, with September typically enjoying milder temperatures ranging from a minimum of 6°C (42°F) to a maximum of 26°C (78°F), averaging at 14°C (57°F). In contrast, March experiences cooler temperatures, characterized by a minimum of -5°C (23°F) and a maximum of 16°C (61°F), with an average of 7°C (44°F). Both months see significant precipitation, with September receiving about 146 mm (5.7 in) over 18 days, while March has slightly higher rainfall at 152 mm (6.0 in) over 19 days. Humidity levels are notably similar, hovering around 85% in September and 86% in March, which adds to the overall dampness in both months. For a more detailed look at the weather variables in March, you can check out Llanberis weather in March.

September and April present notable contrasts in weather conditions. In September, temperatures range from a minimum of 6°C (42°F) to a maximum of 26°C (78°F), with an average of 14°C (57°F), making it generally warmer than April, where the temperature ranges from a chilly 0°C (33°F) to a maximum of 19°C (66°F) and an average of 8°C (47°F). Additionally, September experiences significantly higher precipitation, totaling 146 mm (5.7 in) across 18 days, while April sees less rainfall, with 62 mm (2.4 in) spread over 12 days. Humidity levels remain relatively similar, with September at 85% and April at 84%. For more detailed insights on April weather, you can refer to Llanberis weather in April.

When comparing the weather between September and May, September tends to be milder overall, with average temperatures around 14°C (57°F) compared to May's average of 11°C (52°F). September also boasts higher maximum temperatures, reaching up to 26°C (78°F), while May peaks at 23°C (73°F). However, September is characterized by significantly more rainfall, with 146 mm (5.7 in) of precipitation over 18 days, in contrast to May's 87 mm (3.4 in) over 12 days. Additionally, humidity levels are slightly higher in September at 85%, compared to 79% in May. For a more detailed look, you can check this link: Llanberis weather in May.

When comparing the weather in September and June, we can observe that both months have similar average temperatures, with June experiencing slightly higher minimum and maximum temperatures. In September, temperatures range from a minimum of 6°C (42°F) to a maximum of 26°C (78°F), while June ranges from 7°C (46°F) to a maximum of 26°C (79°F). Precipitation is more frequent in September, with 146 mm (5.7 in) over 18 days compared to June's 106 mm (4.2 in) over 16 days, leading to slightly higher humidity levels in September at 85% compared to June’s 81%. Overall, June tends to offer a drier and less humid experience compared to September. For a detailed look at June weather in Llanberis, you can check out Llanberis weather in June.

In comparing the weather of September and July, September tends to be cooler, with minimum temperatures dropping to 6°C (42°F) compared to July's 9°C (48°F). The average temperature in September is slightly higher at 14°C (57°F) but reaches a maximum of 26°C (78°F), just above July's max of 25°C (77°F). Precipitation also increases in September, totaling 146 mm (5.7 in) over 18 days, while July sees less rain at 105 mm (4.1 in) over 15 days. Additionally, September has higher humidity levels at 85%, compared to July's 78%. For more detailed information about July weather, you can visit Llanberis weather in July.

In comparing the weather between September and August, September typically experiences cooler temperatures, with a minimum of 6°C (42°F) and an average of 14°C (57°F), compared to August's minimum of 9°C (49°F) and average of 15°C (60°F). While September sees a maximum temperature of 26°C (78°F), August's maximum is slightly lower at 24°C (75°F). Precipitation levels are notably high in both months, with September recording 146 mm (5.7 in) over 18 days, while August has 162 mm (6.4 in) over 22 days. Additionally, September has a higher humidity level at 85% compared to August's 79%. For more detailed weather patterns, you can check Llanberis weather in August.

September and October present notable contrasts in weather. In September, temperatures range from a mild minimum of 6°C (42°F) to a warm maximum of 26°C (78°F), with an average of 14°C (57°F). The month sees a significant amount of rainfall, totaling 146 mm (5.7 in) across 18 days, with humidity levels around 85%. In contrast, October experiences cooler temperatures, with lows dropping to 1°C (33°F) and an average of 11°C (53°F), peaking at 20°C (68°F). Precipitation increases to 206 mm (8.1 in), occurring over 22 days, and humidity rises to 90%. For more details, you can check Llanberis weather in October.

September and November exhibit distinct weather patterns. In September, temperatures range from a minimum of 6°C (42°F) to a maximum of 26°C (78°F), with an average of 14°C (57°F). The month experiences significant rainfall, totaling 146 mm (5.7 in) over 18 days, and a humidity level of 85%. In contrast, November cools down considerably, with temperatures ranging from 1°C (34°F) to 14°C (58°F), averaging just 8°C (48°F). The precipitation increases to 176 mm (6.9 in) over 21 days, accompanied by a slight rise in humidity to 91%. For a closer look at what to expect, check out Llanberis weather in November.

September weather in Llanberis is characterized by milder temperatures, with a minimum of 6°C (42°F) and an average of 14°C (57°F), peaking at 26°C (78°F). The month experiences considerable rainfall, totaling 146 mm (5.7 in) over 18 days, and the humidity averages around 85%. In contrast, December brings colder conditions, with temperatures dropping to a minimum of -2°C (29°F) and an average of 7°C (45°F), reaching a maximum of 12°C (54°F). This month sees even more precipitation, accumulating 203 mm (8.0 in) across 24 days and slightly higher humidity at 89%. For more detailed insights, you can check Llanberis weather in December.

Compare Llanberis's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Llanberis

As summer gives way to autumn, Llanberis experiences a notable shift in weather during September. The days are still warm, with occasional peaks reminiscent of summer, yet the evenings cool down significantly, creating a delightful contrast. With a high humidity level and frequent rain, this month stands out for its lush, vibrant landscapes, as nature prepares for the change in season. While the average temperature is milder, the increased precipitation days contribute to the lush scenery that Llanberis is famous for. September's transitional character makes it unique among the months, offering visitors a chance to witness the beauty of the Welsh landscape in all its glory. For more insights on what to expect, visit Llanberis Climate.