10°C or less and I set the time I can comfortably be in water without the wetsuit as 1 minute for every degree, so 5 degrees, 5 minutes. Fairly straight-forward. But if it is a sunny day that time can extend out several minutes as it is surprising how much warmth the sun gives both to the water and of course drying afterwards. The trick is not to outstay the welcome.
Today is one such gloriously sunny day and there is not a hint of breeze. The sea oozes crudely like oil, but, unlike oil, it is clear (up to a point) and bottle green in the depths. Diving from the rocks into the green depths I hardly notice the sharp chill. Re-surfacing and the water behind me effervesces.
I swim off under the cliff where the low winter sunshine blinks at me through the bare trees and dips and rises above the edge of the cliff as the gentle swell lifts and drops me.
The rocks here have been gnawed by barnacles and dissolved by seawater so as to become deep pitted and sharp fluted. It is fascinating to look at but painful to bump into and after just a few moments in the water my fingers and toes are already numbing with the chill and I know from experience I would not feel a thing if I were to grate across the surface, only feeling it later when I notice the blood.
The beach opens up ahead where there are a few walkers and their dogs, but otherwise it is a typical January mid-day, all quiet on the beach front.
My fingers and toes are really numb now and clambering out over the sharp rocks takes a little more care than usual. I have clearly been in too long as despite the added sunshine there are cold fingers skittering up and down my spine and I have got the shakes, I definitely overstayed my welcome.