I don't know what the season has to do with it, if it is legal then you can go anytime.
Where I am from the weather is so beautiful that my skin has turned from white to bronze, from the miami sun.
Maybe you should vacation here for the winter.
What would the season have to do with the law? Would they relax the law in winter, simply because no sane person will go out there? Or will the police not be there in winter?
I once visited Findhorn community in Scotland, a.t the end of Sept. It was downright cool, but I was determined to find the beach (Firth of Forth) and a.t least walk barefoot in the sand. It was breezy and still sunny. I doffed all my clothing and ran into the water, since no people were on the strand just then. Shivering and happy, I dressed and ran a bit just to warm up.
I hadn't a care if it was LEGAL. If nobody sees me, I've not offended any eyes. If they watched me furtively through a thicket, then they weren't running off to find a policeman, were they? (No cell fones in those days).
And I wasn't doing anything le.wd.
Go to the beach alone: if you can bear the cool breeze, you should be rewarded with a chance to bare your arse and have a joyous event worth remembering.
Once confidant about it, take a friend.