Coastal Normandy is often coolish and overcast (or rainy) even in the middle of summer, so you should have a warm layer of some sort (I have a light fleece jacket) and a waterproof layer (I use a rain jacket). It's very unlikely to be really cold, but the coastal wind could be unpleasant on a cool, rainy day if you got soaked to the skin. For that part of Europe, I'm a fan of waterproof shoes (many others would declare them overkill) and 97% nylon pants that sort of shed water without being waterproof.
Unfortunately, due to climate change, there's a slight possibility you'll encounter a rather hot day or two--though it's probably much more likely to occur later in the month. I see Bayeux hit 90F on June 25, 2023, for example.
I don't trust monthly averages when planning my packing list. Averages hide extremes, and it's the extremes that can make you uncomfortable. I like to look at the actual, historical, day-by-day weather statistics available on the website timeanddate.com. The data normally goes back at least 10 years, and I usually check the most recent 5 years.
Bayeux weather -- June 2023
Use the pull-down box at the right, just above the graph, to change the month/year displayed. Use the Search box to display information for a different location.
