Last updated: January 18, 2025
The climate of St Helier, Jersey, is classified as Cfb according to the Köppen-Geiger climate classification, indicative of a temperate maritime climate. This region experiences a minimum temperature of -2°C (29°F) in March, while the average annual temperature hovers around 13°C (55°F). The warmest month, July, can see temperatures rise to a maximum of 27°C (80°F), highlighting the seasonal variability and inviting milder summers that characterize this picturesque locale.
St Helier, Jersey, showcases a distinct seasonal temperature pattern throughout the year. Winter months, such as January and February, reveal relatively mild temperatures, with averages reaching around 8°C (47°F), and minimums dipping to -2°C (29°F) in March. As spring approaches, temperatures gradually rise, peaking in April with pleasant averages of 10°C (51°F) and maximums of 17°C (62°F). The onset of summer brings significantly warmer conditions, particularly in July, where maximum temperatures can soar up to 27°C (80°F), accompanied by mild nights averaging around 17°C (63°F). As the year transitions into autumn, temperatures begin to cool, with October averaging 15°C (59°F) and maximums gradually declining to 20°C (69°F). This cyclical temperature pattern highlights the maritime influence on St Helier’s climate, ensuring relatively moderate temperatures year-round.
Saint Helier experiences a notable range in temperatures throughout the year, with a minimum of -2°C (29°F) in March and a peak of 27°C (80°F) in July. This variation highlights the transition from the colder early spring to the warmth of mid-summer, making it essential for visitors to prepare accordingly. For more detailed information, you can refer to the monthly temperatures in Saint Helier.
St Helier experiences significant precipitation throughout the year, with the winter months of January and February typically recording higher levels, at 97 mm (3.8 in) and 90 mm (3.5 in), respectively. This trend continues into early spring, although March sees a slight reduction to 84 mm (3.3 in). As the seasons transition, April marks a significant drop in rainfall to only 36 mm (1.4 in), leading to drier conditions that persist into May with 63 mm (2.5 in) and June at 71 mm (2.8 in).
The summer months see a moderate range of precipitation, with July receiving 47 mm (1.9 in) and August slightly higher at 66 mm (2.6 in). However, as autumn approaches, rainfall begins to increase dramatically, with October recording the highest monthly total of 157 mm (6.2 in), followed by November at 125 mm (4.9 in). The year culminates in December, which experiences the highest precipitation level at 185 mm (7.3 in) over 22 days, indicating a trend of increased wetness during the colder months and highlighting the maritime influence on St Helier's climate.
In St Helier, Jersey, sunshine duration demonstrates a clear seasonal pattern, with notable increases from winter to summer. The year begins with January offering only 104 hours of sunshine, which gradually rises through February (166 hours) and March (239 hours). This upward trend becomes pronounced with the arrival of spring, as April accumulates an impressive 356 hours and May reaches a peak of 412 hours. These months mark the transition into longer, sunnier days, laying the groundwork for the summer season.
The summer months uphold this sunny trend, with July shining brightly at 432 hours, the highest total for the year. August follows closely, recording 392 hours before the days begin to shorten again in September with 334 hours. As autumn approaches, sunshine hours diminish further, with October dropping to 270 hours and November seeing a notable decline to 184 hours. By December, sunshine retreats to 132 hours, highlighting a stark contrast with the peak summer months. Overall, the sunshine data emphasizes St Helier's vibrant summer days, while also reflecting the diminished daylight hours characteristic of the winter season.
In St Helier, Jersey, the UV Index reflects a notable seasonal variation in sun exposure and the potential risk of skin damage. During the winter months, January and December present relatively low UV levels, with indices of 2 and 1, respectively, indicating minimal risk and requiring longer burn times of 45 minutes. As winter transitions into spring, the UV Index begins to rise, reaching 3 in February and peaking at 4 by March, both categorized as moderate levels. This gradual increase emphasizes the necessity for sun protection as exposure becomes more intense.
The arrival of summer heralds a sharp rise in UV radiation, particularly in June and July, where the UV Index peaks at 9, categorized as very high, and burn times reduce significantly to just 15 minutes. August follows closely with a UV Index of 8, indicating continued high sun intensity. As autumn approaches, UV levels begin to decrease, tapering down to 6 in September and dropping to 4 by October, before returning to low levels in November and December. This seasonal trend highlights the importance of vigilant sun protection during the peak summer months when the risk of skin damage is significantly heightened.
UV Risk Categories
Daylight duration in St Helier, Jersey, exhibits a characteristic seasonal cycle, beginning with the shorter days of January, which offer only 8 hours of sunlight. As February approaches, daylight increases to 10 hours, signaling the gradual return of longer days. The transition into spring further enhances daylight, with March featuring 11 hours and April providing 13 hours, culminating in May at 15 hours. This steady ascent highlights the lengthening of days as spring gives way to the more sun-soaked months.
The peak daylight duration occurs in June, with an impressive 16 hours of sunlight, offering the longest days of the year. Although daylight begins to decline in July to 15 hours, it remains substantial throughout the summer months. August sees a slight reduction to 14 hours, while September presents 12 hours. As autumn progresses, daylight hours continue to wane, dropping to 10 hours in October and descending further to 9 hours in November. The cycle concludes with a return to 8 hours of daylight in December, underscoring the rhythmic nature of sunlight availability throughout the year in St Helier.
Saint Helier, Jersey experiences a temperate maritime climate, characterized by mild winters and warm summers. Average temperatures range from 2°C (35°F) in January to 27°C (80°F) in July. The area receives significant rainfall, particularly in the autumn, with October recording the highest precipitation at 157 mm (6.2 in). Sunshine is prevalent, especially in the summer months, peaking at 432 hours in July. For more detailed information, please refer to the Saint Helier climate.
In conclusion, St Helier, Jersey, presents a dynamic climate characterized by distinct seasonal variations in temperature, precipitation, sunshine duration, UV Index, and daylight hours. The transition from the mild, wet winters to vibrant summers illustrates the region's temperate maritime climate, offering both residents and visitors a diverse palette of natural conditions. The notable increase in sunshine and daylight during the summer months, coupled with heightened UV exposure, highlights the importance of sun protection and outdoor enjoyment during this period. Conversely, the colder months serve as a reminder of the need for adaptation in response to changing light and weather patterns. Understanding these climatic factors is crucial for making the most of St Helier's unique environment throughout the year.