 Sea temperature at the islands varies according to a diurnal cycle, with the water at its coldest between six and eight in the morning, and at its warmest between three and four in the afternoon.In summer the daily temperature range is around 1 °C (2 °F); in winter it is about half that.There is also an annual cycle, with sea temperature varying by a little less than 4 °C (7 °F) over the year, peaking at nearly 24 °C (75 °F) in March, and falling to around 20 °C (68 °F) in September.