Last updated: August 21, 2025
September in Saint Helier, Jersey is characterized by a pleasant average temperature of 17°C (63°F), with daily highs peaking at 23°C (75°F) and lows dropping to 12°C (54°F). This transitional month experiences an average humidity of 79%, making the air feel comfortably mild, though occasional rainfall is common. With 82 mm (3.2 in) of precipitation spread over 11 days, residents and visitors alike can expect a mix of sunny spells and refreshing showers. Overall, September offers a delightful atmosphere for enjoying the beauty of Jersey before autumn settles in.
As September arrives in Saint Helier, Jersey, temperatures begin to transition subtly from the warmth of summer to the refreshing hints of autumn. With minimums averaging around 12°C (54°F), it's still mild enough for outdoor activities, while the average temperature settles at a comfortable 17°C (63°F). The peaks reach about 23°C (75°F), allowing for those last sunny days at the beach or leisurely strolls through the charming streets. This month marks a delightful balance, as it retains some warmth from August but hints at the cooler weather to come in October, making it an ideal time for visitors to enjoy the lingering summer vibes before the seasonal shift.
In September, Saint Helier, Jersey experiences a notable shift in precipitation patterns, with an average of 82 mm (3.2 in) of rain over 11 days. This places September in the middle tier of the yearly rainfall totals, reflecting a subtle transition from the earlier, drier summer months. Compared to the heavier rain seen in October, which averages 157 mm (6.2 in), September's precipitation signals the onset of autumn, as it typically serves as a bridge to the wetter months ahead. Notably, while there is an uptick in rain days from the summer, the overall volume doesn't reach the extremes of late autumn, suggesting that September remains a relatively moderate month in terms of weather throughout the year.
In September, Saint Helier experiences a moderate drop in humidity, with levels settling around 79%. This slight decrease follows the summer months, where humidity peaks at 73% in August, indicating a transition toward the wetter autumn season. As the year progresses, September's humidity remains higher than both the mid-summer months and the drier spring months, such as April and May, but is significantly lower than the winter months, which soar back to 89-92%. This pattern reflects the island's characteristic climate, offering an inviting balance as summer warmth fades and the chill of October approaches.
In September, Saint Helier experiences a transition in UV levels, reflecting the changing seasons. With a UV Index of 6, categorized as high, residents and visitors should remain vigilant about sun exposure, particularly as the burn time is approximately 25 minutes. This month marks a slight decline from the very high levels observed during the peak summer months of June through August, where the index reached up to 9. As autumn approaches, individuals should take care to protect their skin while still enjoying the pleasant early fall weather. For more detailed information on UV exposure and protection in Saint Helier, check out Saint Helier UV Index.
UV Risk Categories
As summer gives way to autumn, September in Saint Helier, Jersey, shines brightly with an impressive 334 hours of sunshine. This delightful month follows a sun-drenched summer, peaking in July with 432 hours, and gracefully transitioning into October. While the daylight hours begin to wane, September still offers a robust experience, significantly outshining the winter months ahead, which see just 270 hours in October and drop further to 184 hours in November. The generous sunshine in September, although slightly diminished from the vibrant heights of summer, invites residents and visitors alike to bask in the lingering warmth and beauty of the season's final days.
When considering the likelihood of sunny weather in September in Saint Helier, Jersey, you'll find that early autumn still holds promise for bright days, with a 43% chance of sunshine. This marks a slight uptick in sunny conditions compared to the summer months, such as July and August, which hover around 41%. Interestingly, September's sunshine probability remains relatively robust, especially when contrasted with the winter months; for instance, the chance of sun drops to 20% in January and around 25% in December. This trend suggests that while the summer warmth begins to fade, September continues to offer a compelling opportunity for delightful sunny moments in this picturesque locale.
As the summer sun begins to wane in September, Saint Helier, Jersey, enjoys around 12 hours of daylight, marking a gentle transition into the autumn months. Following the peak of 16 hours in June, daylight gradually decreases, with September’s hours still providing ample opportunity for outdoor exploration and enjoyment. This month bridges the gap between the long summer days and the shorter daylight hours of October, which sees a drop back to 10 hours. The gradual decline in daylight from September onwards reflects the rhythm of the changing seasons, inviting residents and visitors alike to savor the lingering warmth of early fall before the darker days of winter set in.
As summer fades into autumn, September in Saint Helier, Jersey, brings a gentle breeze that feels like a soft transition. With an average wind speed of 5.6 m/s (13 mph), September is among the calmer months, notably cooler than the lively currents of June and July. This delicate drop in wind speed mirrors the tranquil shift in the season, as nature prepares for the brisker days ahead. Interestingly, while January and December experience stronger gusts—averaging 7.8 m/s (17 mph) and 8.7 m/s (19 mph), respectively—September offers a serene reprieve before the winds pick up again in October. This gradual ebb and flow not only paints a picture of the shifting seasons but also hints at the upcoming landscape changes, as the island gears up for fall's embrace.
Weather in Saint Helier varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Saint Helier, focusing on differences in temperature, rainfall, humidity, and UV levels.
In September, the weather tends to be milder, with average temperatures ranging from a minimum of 12°C (54°F) to a maximum of 23°C (75°F), and an average of 17°C (63°F). The month experiences 82 mm (3.2 in) of precipitation over approximately 11 days, coupled with a humidity level of 79%. In contrast, January is substantially cooler, with temperatures dropping to a minimum of 2°C (35°F) and peaking at 13°C (56°F), averaging around 8°C (47°F). The month also sees a higher precipitation total of 97 mm (3.8 in) over about 14 days, and humidity increases to 90%. For more detailed information, visit Saint Helier weather in January.
September and February exhibit stark contrasts in weather patterns. In September, temperatures range from a mild 12°C (54°F) at night to a comfortable 23°C (75°F) during the day, with an average of 17°C (63°F). This month experiences 82 mm (3.2 in) of precipitation over about 11 days and maintains a humidity level of 79%. In contrast, February presents a much chillier climate, with temperatures ranging from a low of -1°C (31°F) to a high of 13°C (56°F), averaging just 8°C (47°F). Precipitation increases slightly to 90 mm (3.5 in) across 16 days, accompanied by higher humidity at 89%. For more detailed insights into February weather, check out Saint Helier weather in February.
September and March exhibit quite contrasting weather patterns. In September, the temperatures range from a mild 12°C (54°F) at night to a comfortable 23°C (75°F) during the day, accompanied by an average humidity of 79%. Precipitation in this month totals 82 mm (3.2 inches) over about 11 days, making it relatively pleasant for outdoor activities. In contrast, March is much cooler, with temperatures fluctuating from a chilly -2°C (29°F) at night to a maximum of 14°C (58°F) during the day. The month sees slightly higher precipitation at 84 mm (3.3 inches) spread over 15 days, and the humidity is also higher at 86%. For more information on March weather, you can visit Saint Helier weather in March.
When comparing the weather in September and April, a significant difference in temperatures is evident. September boasts a milder climate with minimum temperatures around 12°C (54°F) and averages peaking at 17°C (63°F), while April tends to be cooler, with temperatures ranging from a minimum of 5°C (41°F) to an average of 10°C (51°F). Additionally, September experiences higher precipitation levels, with 82 mm (3.2 in) spread over 11 days, compared to April's more modest 36 mm (1.4 in) over 8 days. Despite slightly higher humidity in April at 84%, September's humidity sits closely at 79%. For more details on April's weather, you can refer to Saint Helier weather in April.
When comparing the weather of September and May, September tends to be warmer with an average temperature of 17°C (63°F), peaking at 23°C (75°F), while May has a cooler average of 13°C (55°F), reaching a maximum of 20°C (69°F). September also experiences more rainfall, averaging 82 mm (3.2 in) over 11 days, compared to May's 63 mm (2.5 in) over 10 days. Humidity levels are similar in both months, with September at 79% and May slightly higher at 80%. For more detailed insights, you can check Saint Helier weather in May.
When comparing the weather in September and June, September presents slightly warmer conditions with average temperatures reaching 17°C (63°F), compared to June's average of 15°C (60°F). Although both months experience mild temperatures, September features a higher maximum temperature of 23°C (75°F) versus June's 24°C (76°F). In terms of precipitation, September receives a bit more rainfall with 82 mm (3.2 in) over 11 days, while June has 71 mm (2.8 in) over 10 days. Humidity levels are quite similar in both months, with September at 79% and June at 80%. For a more detailed overview of June weather, you can check Saint Helier weather in June.
In comparing the weather of September and July, September tends to be cooler overall, with temperatures ranging from a minimum of 12°C (54°F) to a maximum of 23°C (75°F). In contrast, July enjoys slightly higher temperatures, with a minimum of 14°C (58°F) and a maximum of 27°C (80°F), making it the warmer month. July also experiences less precipitation at 47 mm (1.9 in) over 9 days, compared to September's 82 mm (3.2 in) over 11 days, indicating that September is typically wetter. Additionally, the humidity levels are higher in September at 79%, compared to July's 69%. For more details about July's weather, you can check Saint Helier weather in July.
September experiences slightly cooler temperatures compared to August, with average highs of 23°C (75°F) compared to August's 25°C (78°F). The minimum temperatures in September are also lower, averaging 12°C (54°F) versus 14°C (57°F) in August. Additionally, September sees increased precipitation, with 82 mm (3.2 in) falling over 11 days, while August has 66 mm (2.6 in) of rain across 13 days. The humidity is also higher in September at 79%, compared to 73% in August. For more detailed information on August weather, you can check out Saint Helier weather in August.
September typically offers a milder climate with average temperatures ranging from 12°C (54°F) to 23°C (75°F) and lower precipitation at 82 mm (3.2 in) over about 11 days. In contrast, October sees a noticeable drop in temperature, with averages between 9°C (48°F) and 20°C (69°F), and experiences more rainfall, totaling 157 mm (6.2 in) across 19 days. Additionally, the humidity increases from 79% in September to 89% in October, contributing to the overall chill in the air. For a more detailed overview of October's weather, you can check Saint Helier weather in October.
September and November showcase a notable shift in weather patterns. September enjoys milder temperatures, with a minimum of 12°C (54°F) and an average of 17°C (63°F), whereas November sees a drop, with a minimum of 5°C (41°F) and an average of only 12°C (53°F). Precipitation increases from 82 mm (3.2 in) over 11 days in September to 125 mm (4.9 in) across 18 days in November, reflecting a wetter and gloomier atmosphere. Additionally, humidity rises from 79% in September to 92% in November, contributing to the cooler and damp conditions of late autumn. For more detailed weather information, you can visit Saint Helier weather in November.
September and December present notably different weather patterns. In September, temperatures generally range from a minimum of 12°C (54°F) to a maximum of 23°C (75°F), making it a milder month with an average temperature of 17°C (63°F). Precipitation during this time is around 82 mm (3.2 in) over 11 days, accompanied by a humidity level of 79%. In contrast, December experiences much cooler temperatures, with a minimum of 3°C (38°F) and a maximum of only 14°C (57°F), resulting in an average of 10°C (50°F). The month is significantly wetter, receiving 185 mm (7.3 in) of rain over 22 days, and the humidity rises to 92%. For those interested in exploring the specific weather conditions of December, more information can be found at Saint Helier weather in December.
As September arrives in Saint Helier, the weather begins to transition from the warmth of summer to the cooler embrace of autumn. While the maximum temperatures can still reach a pleasant 23°C (75°F), the average cools down to a comfortable 17°C (63°F), offering a refreshing change compared to the peak summer months. September typically experiences an increase in humidity, averaging around 79%, with rain making its appearance on about 11 days throughout the month. These conditions create a unique atmospheric charm that blends the tail end of summer's warmth with the upcoming fall season. For more insights on how the weather shapes this picturesque location, visit Saint Helier Climate.