A northeasterly flow prevails over the South of the basin. Over the North, it is southwesterly, moderate and very variable.
For Penthièvre :
No gale warning.
For the night from Thursday to Friday NNE force 3 in the early part of the night becoming NE force 2. Gusts reaching 13 knots in the early part of the night.
Slight sea. Low, short swell from W. Excellent visibility becoming good in the middle of the night. Daytime of Friday 18 september : The weather will be good.
Cloud and long sunny periods. No precipitation. In the evening, light cloudy spells.
NE force 2 turning SSW in the middle of the day then WNW force 3. Gusts reaching 12 knots in the evening. Slight sea. Low, short swell from W. Good visibility becoming excellent in the middle of the day then good.