Last updated: August 21, 2025
September in Castel, Guernsey, offers a delightful transition into autumn, featuring a maximum temperature of 21°C (71°F) and an average of 17°C (62°F). The season signals cooler evenings, with a minimum temperature dipping to 12°C (54°F). Although this month welcomes some rain, with 63 mm (2.5 in) spread over 9 days, the humidity remains relatively high at 76%, creating a refreshing atmosphere. Whether enjoying the crisp air or the occasional rainfall, visitors and locals alike can appreciate the unique charm of Castel during this time.
As summer fades, September in Castel, Guernsey offers a comfortable and inviting climate, with temperatures settling into a pleasant rhythm. The month begins with a minimum of 12°C (54°F), gradually warming to an average of 17°C (62°F) and peaking at a maximum of 21°C (71°F). This marks a subtle transition from the warmer August days, yet remains a delightful time for outdoor activities. The continued warmth, alongside the cooling waters of the surrounding seas, creates a unique blend of seasonal charm, making September a lovely time to explore the coastal beauty and vibrant scenery of this picturesque island. Overall, this month reflects a smooth descent into autumn while still retaining the warmth of summer.
In September, Castel, Guernsey, receives an average precipitation of 63 mm (2.5 in) across 9 days, marking a noticeable increase from the drier summer months. This transition signals the onset of autumn, as rainfall begins to rise towards the wetter October, which sees a significant jump to 144 mm (5.7 in). Compared to the relatively light showers of earlier months, September’s precipitation hints at a shift in weather patterns, paving the way for the more abundant rains typical of later fall. With September acting as a bridge between the warm summer and the cooler, moisture-rich autumn, residents can expect more frequent, though moderate, rainfall as the season progresses.
In September, Castel, Guernsey experiences a noticeable transition in humidity levels, moderating to 76% as summer draws to a close. This marks a shift from the relatively dry conditions of July and August—where humidity levels dipped to 63% and 71%, respectively—indicating the onset of autumn. The trend reveals a gradual increase in humidity as the year progresses, with a return to higher levels in October at 89% and persisting through the winter months. Such fluctuations reflect the island’s maritime climate, where the air becomes moister as the seasons evolve, enhancing the lush, verdant landscapes that Guernsey is known for.
As summer transitions into autumn, September in Castel, Guernsey continues to see a notable high UV Index of 6. This indicates that while the sun's intensity is diminishing compared to the peak summer months, the risk of harm from unprotected sun exposure remains significant. With a burn time of just 25 minutes, it's crucial to stay vigilant and protect your skin, especially during peak hours. The trend this month mirrors August, where the UV levels were also high, but drops from the very high levels seen in June and July. As the season changes, it's a reminder to regularly check the UV Index and adjust your sun safety practices accordingly. For more detailed information, visit the Castel UV Index.
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September in Castel, Guernsey, bathes the island in 338 hours of sunshine, marking a delightful transition from the vibrant summer months. Following the peak of 436 hours in July, the sun's embrace begins to soften, yet September still boasts ample bright days, making it a perfect time to enjoy the lingering warmth of early autumn. As the days shorten and temperatures dip, the sunshine still holds strong compared to the quieter months ahead, like October with its 270 hours. Overall, the steady decline from summer’s height is a gentle reminder that the beauty of daylight continues well into the fall, inviting visitors to relish in the charm of Castel's early autumn glow.
In September, Castel, Guernsey experiences a moderate 43% chance of sunny weather, making it a pleasant time to enjoy the island's natural beauty. This percentage reflects a slight uptick from the summer months, with August trailing at 42%. Although it doesn't reach the 62% peak of sunshine in April, September still offers a reliable opportunity for sun-soaked outings. As the summer warmth begins to wane and autumn approaches, the weather remains engagingly variable, promising both sunny days and the occasional shower. This transitional month is ideal for visitors looking to savor the last whispers of summer before the cooler temperatures settle in.
As summer fades into autumn, September in Castel, Guernsey, offers a gentle transition with approximately 12 hours of daylight. This marks a notable decline from the long, sun-drenched days of June, which peak at 16 hours, and even the more generous 15 hours of July and 14 hours in August. As the days grow shorter, it signals the approach of autumn, where daylight diminishes gradually, bringing the cozy charm of shorter days. The trend from summer to autumn reflects a rhythmic cycle of light that enchants residents and visitors alike, inviting them to savor the remaining warmth of the year before the chill of October settles in, offering just 10 hours of daylight.
As summer transitions to autumn in Castel, Guernsey, September's winds bring a gentle whisper with an average speed of 6.1 m/s (14 mph). This notable dip from the more vigorous gusts of the earlier months reflects a seasonal shift; the wind speeds peak in December at 9.8 m/s (22 mph) and generally maintain a higher average during the winter months. In contrast, the calmest winds are typically found from June to August, when September's breezes begin to signify a gradual return to stronger, more invigorating gusts as autumn takes hold. The month serves as a gentle reminder of nature's rhythm, bridging the calmness of summer's end and the bracing winds that will soon accompany the changing seasons.
Weather in Castel varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Castel, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January present notably different weather patterns. September enjoys milder temperatures, with an average of 17°C (62°F), while January is considerably cooler, averaging just 9°C (49°F). In September, the minimum temperature is a comfortable 12°C (54°F), compared to the chilly 3°C (37°F) minimum in January. Precipitation is more frequent in January, with rain falling on 14 days and totaling 94 mm (3.7 in), compared to 63 mm (2.5 in) over 9 days in September. Additionally, humidity is higher in January at 89%, compared to 76% in September, contributing to a more damp and cold atmosphere during the winter month. For more detailed insights on January weather, you can check Castel weather in January.
In comparison to September, February brings significantly cooler temperatures, with highs averaging only 13°C (56°F) compared to September's 21°C (71°F). The minimum temperature in February drops to 0°C (33°F), while September maintains a milder low of 12°C (54°F). Additionally, February experiences more frequent rainfall, with 86 mm (3.4 in) over 16 days, compared to September's 63 mm (2.5 in) over just 9 days. The humidity also rises in February to 88%, compared to September's 76%. For more details on the weather conditions during this time, you can visit Castel weather in February.
September generally offers milder temperatures compared to March, with average highs reaching up to 21°C (71°F) while March peaks at only 13°C (55°F). However, March experiences slightly more precipitation, with 73 mm (2.9 in) spread across 15 days, compared to September's 63 mm (2.5 in) over 9 days. Humidity levels are also higher in March, averaging 85%, versus September's 76%. For a detailed look at March weather patterns, you can visit Castel weather in March.
In comparison to September, April experiences significantly cooler temperatures, with a minimum of 5°C (41°F) and a maximum of 15°C (59°F), contrasted with September’s milder range of 12°C (54°F) to 21°C (71°F). Additionally, April sees less precipitation overall, with 34 mm (1.3 in) over 8 days, while September has 63 mm (2.5 in) falling over 9 days. The humidity levels are also slightly higher in April at 84% compared to 76% in September. For more detailed information about the weather conditions during April, you can visit Castel weather in April.
When comparing the weather in September to that of May, September generally offers warmer temperatures, with daily averages reaching around 17°C (62°F), compared to May's cooler 12°C (54°F). The maximum temperatures in September can climb up to 21°C (71°F), whereas May peaks at 18°C (65°F). In terms of precipitation, September experiences slightly more rainfall with 63 mm (2.5 in) over 9 days, while May sees 55 mm (2.2 in) over 8 days. Additionally, both months maintain high humidity levels, though September is slightly lower at 76% compared to May's 81%. For more detailed information about the weather in May, you can check Castel weather in May.
In comparing the weather of September and June, September generally offers warmer temperatures, with an average of 17°C (62°F) compared to June's 14°C (58°F). While both months experience similar humidity levels—76% in September and 77% in June—September tends to have slightly more precipitation, with 63 mm (2.5 in) over 9 days, versus June's 59 mm (2.3 in) over 8 days. Overall, September's warmer temperatures make it more comfortable, despite a bit more rainfall. For further details, you can check out Castel weather in June.
In comparing the weather of September and July, we see some notable differences. September experiences a slightly wider temperature range, with minimums around 12°C (54°F) and maximums reaching 21°C (71°F), while July has temperatures varying from a minimum of 14°C (57°F) to a maximum of 21°C (70°F). Precipitation is more frequent in September, occurring on about 9 days with a total of 63 mm (2.5 in), compared to July's lighter rainfall of 37 mm (1.5 in) over 7 days. Additionally, September tends to be more humid, with an average humidity of 76%, versus July's 63%. For a deeper look at July weather, you can visit Castel weather in July.
In comparing the weather of September to August, September tends to be slightly cooler, with minimum temperatures dropping to 12°C (54°F) compared to August's 14°C (57°F). While both months have similar average temperatures of around 17°C (62°F), September sees a maximum temperature of 21°C (71°F), just a degree lower than August's peak of 22°C (72°F). Additionally, September experiences more precipitation, with 63 mm (2.5 in) over 9 days, compared to August's 50 mm (2.0 in) also over 9 days. Humidity levels are higher in September at 76%, compared to August’s 71%, indicating a more humid atmosphere as summer transitions into autumn. For a more detailed view of August weather, you can check Castel weather in August.
September tends to be milder than October, with average temperatures ranging from a minimum of 12°C (54°F) to a maximum of 21°C (71°F) and an average of 17°C (62°F). In contrast, October sees cooler temperatures, with a minimum of 9°C (48°F), an average of 15°C (59°F), and a maximum of 20°C (68°F). Additionally, October experiences significantly more rainfall, with 144 mm (5.7 in) of precipitation over 17 days compared to September's 63 mm (2.5 in) over 9 days. The humidity also rises in October to 89%, up from September's 76%. For a detailed look at the weather conditions during October, you can visit Castel weather in October.
In comparing the weather of September to November, we see a noticeable drop in temperatures and an increase in precipitation. September enjoys milder temperatures, with average highs around 21°C (71°F) and relatively lower humidity at 76%. However, as November approaches, the temperatures decrease significantly, averaging only 12°C (54°F), with maximums reaching 17°C (63°F) and a marked increase in humidity to 90%. Additionally, November experiences nearly double the rainfall, with 126 mm (5.0 in) spread over 18 days compared to September's 63 mm (2.5 in) over just 9 days. For more detailed insights, you can visit Castel weather in November.
September and December present distinct weather patterns. In September, temperatures range from a mild minimum of 12°C (54°F) to an average of 17°C (62°F), peaking at around 21°C (71°F). The month sees about 63 mm (2.5 in) of precipitation over 9 days, accompanied by a humidity level of 76%. In contrast, December experiences much cooler weather, with temperatures dipping to a minimum of 5°C (41°F), averaging 11°C (51°F), and maxing out at 14°C (58°F). This month is significantly wetter, with 163 mm (6.4 in) of precipitation spread across 21 days and a higher humidity level of 90%. For more detailed insights, you can check Castel weather in December.
As September rolls in, Castel experiences a notable transition in weather, ushering in cooler temperatures and a higher chance of rain compared to the summer months. With an average temperature of 17°C (62°F), the days become refreshingly crisp, particularly in contrast to the warmth of July and August. While September still enjoys some sunny spells, it also sees an increase in humidity and 63 mm of precipitation spread across about 9 days, making it a month of change as nature begins to hint at autumn. For a deeper dive into Castel's climate nuances, be sure to check out Castel Climate.