Geography of Jersey

Jersey (Jèrriais: Jèrri) is the largest of the Channel Islands, an island archipelago in the St. Malo bight in the western English Channel. It has a total area of 120 square kilometres (46 mi²) and is part of the British Isles archipelago. It lies 22 kilometres (12 nmi; 14 mi) from the Cotentin Peninsula in Normandy, France and about 161 kilometres (87 nmi; 100 mi) from the south coast of Great Britain. Jersey lies within longitude -2° W and latitude 49° N.

It has a coastline of 70 kilometres and no land connections to any other territories. Jersey claims a territorial sea of 3 nmi (5.6 km; 3.5 mi) and an exclusive fishing zone of 12 nmi (22.2 km; 13.8 mi) and shares maritime borders with the Bailiwick of Guernsey to the north and France to the south and east.

Jersey is the main island of the Bailiwick of Jersey, which also consists of islet groups known as Les Écréhous, Les Minquiers, Les Dirouilles and Les Pierres de Lecq.

It is a highly densely populated territory, being the 13th most densely populated country or territory. About 30% of the population of the island is concentrated in the parish of Saint Helier, which contains the main town of the island.

The island has an oceanic climate, with cool to mild winters and lukewarm to warm summers. The highest temperature recorded was 37.9 °C (100.2 °F), on 18 July 2022, and the lowest temperature recorded was −10.3 °C or 13.5 °F, on 5 January 1894. 2022 was the warmest (and sunniest) year on record; the mean daily air temperature was 13.56 °C or 56.41 °F. For tourism advertising, Jersey often claims to be "the sunniest place in the British Isles", as Jersey has over 1,900 hours of sunlight. Jersey is indeed one of the sunniest places in the British Isles, especially during the warmer months, as it is subject to more influence from the Azores High, which acts as a blocking mechanism for depressions that originate in the North Atlantic and that produce stratiform clouds and rain; these are deflected northwards towards the UK mainland. The Azores High further reduces the type of convective cloud formations (particularly Cumulus and Stratocumulus) that are common over more northern and inland areas of the UK during summer through subsidence.

In 2011, Jersey generated controversy for calling itself "the warmest place in the British Isles" during an advertising campaign, as Jersey is neither the place with the highest maximum temperature in the British Isles (40.3 °C or 104.5 °F was recorded in Coningsby, Lincolnshire in July 2022) or the highest winter temperatures in the British Isles (which would be the Isles of Scilly).

Typical wind speeds vary between 20 kilometres per hour (12 mph) and 40 kilometres per hour (25 mph). During the cooler months, extratropical cyclones can produce gales somewhat regularly.

Snow is very rare in Jersey. The last significant snowfall event occurred in March 2013, when 14 centimetres (5.5 in) fell. The most recent measurable snowfall occurred on 8–9 January 2024, when 3 to 5 centimetres (1.2 to 2.0 in) fell. Initially, a fall of only 0.5 cm (0.20 in) had been forecast, so the event was more significant than expected.