Why are sea temperatures off France’s coasts so abnormally high?
They are between 3C to 5C higher than usual in the Atlantic and Mediterranean for this time of year, say experts
Sea temperatures are usually lower than the air temperature at the beginning of the summer as the sea takes longer to heat up
SYLVAIN FELTEN / Shutterstock
If you have taken a dip in the sea off France's Mediterranean or Atlantic coasts recently, you might have been pleasantly surprised by the temperature of the water.
You were probably not imagining things: French weather experts on Wednesday (June 14) reported the temperature of the Mediterranean Sea off the French coast varied from 22 C to 24 C, while Atlantic temperatures varied between 17C to 22C.
Meteorologist Guillaume Séchet said the temperatures are between 3C to 5C higher than usual for this time of year.
Sea temperatures are usually lower than the air temperature at the beginning of the summer as the sea takes longer to heat up. As a result, sea temperatures usually peak in August after gradually warming up over the summer.
These abnormally high temperatures have not just been registered in France but worldwide, with temperatures for the northern Atlantic Ocean reaching a record high of 1.2 C above average last Saturday (June 10).
France’s weather service, Météo France, has noted the number of marine heat waves “has doubled since 1982, and their intensity has increased”.
Read also: Warning over heightened risk of forest fires in northern France
Weak winds
So what has caused these abnormally high temperatures?
According to weather experts, a weather phenomenon, called an anticyclone, is abnormally weaker than usual, meaning the trade winds that blow over the Atlantic are also weaker than usual. As a result, there are completely calm areas in the Atlantic Ocean, which absorb more heat than choppier areas.
Not only do these trade winds churn up the ocean and encourage water to evaporate, both of which help temperatures to drop, but they also bring sand from the Sahara which reduces sun exposure, again keeping temperatures low.
French weather website meteo-villes said it is difficult to know how the situation will change in the next few months and what the consequences will be for France. However, these abnormally warm waters do mean there is more energy for potential hurricanes.
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