You would be forgiven into thinking that the sea temperature is at its mildest on the hottest days of the year. In fact, this is not true.
With the average temperature of the sea in September at a balmy high of 17.4°C and coldest in March when the average of around 8°C, you might be left thinking how and why!
In very simple terms: the sea takes a lot warmer to heat up than air and so will gradually warm up over the summer months. And like it takes longer to heat, it also takes longer to cool, so for most of the coast in the UK, the sea will be at its coldest just as Spring begins – before the gentle increase in temperature starts again!
With temperatures of the sea never falling close to the temperatures of smaller bodies of water like lakes, it is a popular choice for swimmers throughout the year.
Take a look at our chart below which shows the minimum and maximum average temperatures for the months throughout the year.
