This is one piece of gear you're going to want whether you're sailing in cold places or warm. That may sound odd, until you realise that their purpose isn't to protect from cold but from rope burns.
I'll start with this photo, that shows a pair of gloves after about two to three weeks of use:
Those worn out parts are caused by our hands constantly rubbing against rope. Originally the gloves were entirely black like the palm part.
Another reason why gloves are essential - they help increase grip, which is important when you don't want ropes holding sails in to slip through your fingers accidentally!
It is of course entirely possible to sail without gloves, and when the wind is light (or in smaller, less powerful boats) - in both cases meaning less pressure on the fingers - I'm sure many people do. After all, bare hands have better feel for the minute changes in tension on the sheets (that's what we call the main ropes or lines that hold the sails) that indicate changes in wind pressure against the sail. That's important when you want to be accurate on fine tuning.
My gloves are a kind of compromise. They are really thin, but the black bit you see in the picture is really good grippy material, so I get help with gripping sheets, the sheets don't chafe direction against my skin, but not quite the same level of comfort as thicker gloves. What I find with thicker gloves (which I use to use before I tried these), is that they're a little tougher to grip through, possibly because it's harder to feel the direct pressure of the rope against your hand.
I don't have a pair of these now to photograph, but those that I'm putting on in the picture were the gloves I used until the end of 2010. Thicker material, half-fingered (which had the unfortunate effect of slipping lower when they got old and then leaving the middle sections of my fingers occasionally exposed). They lasted longer, though, because of the material thickness. In 2011 I switched to my current pair of Zhik brand gloves, just testing at first, and then I decided to stick with these.
And I tape round my fingers at the spots where there is often extra pressure against them.
(Ignore the nails; the picture was actually taken because I was sort of celebrating National Day while overseas.)
The taping was a habit from the old half-finger gloves, so that if they slipped the taped areas would still have some protection. It can get pretty nasty if my fingers have prolonged rubbing against rope. Strangely, it's not like an even abrasion. Somehow it forms a split right down the skin so that it looks like a cut. You can actually see where the flesh splits. I never took any photos of them and I don't think you'd want to see it anyway!