A lot of variables. For fun I`ll go out in up to 20knots but if gusts are over 22 I`ll think twice. Racing is much the same, but will stay out up to 25-28knots, or until I have capsized myself into a really bad placing or am overfatigued from righting the boat,typically after 4 times it gets tiring. Take 5knots off all the above for singlehanding. If I think the boat is working too hard, chop state etc, I will call it off. I will also try and finish any race I have started, recently was one of 3 finishers in a 15 boat race, but I felt in control or would have called it off.
Sailed Cape Point Challenge in 25knots gusting 30 at the startline, some events are worth pushing a little past the safety margins for .
BUT :
I sail a boat with what most consider too little sail area for it`s size, a short mast (7,3m as opposed to the 8,5m F16 mastlength maximum),and I can right it solo in all conditions, only fear is separation from the boat. (have capsized 4 times in one race, and twice in one leg on w/l courses.) If you are confident about righting your boat easily, you will extend the limits at which you sail quite a lot - If I capsize under spinnaker, I`ll right the boat and hoist again without concern for another capsize. Only downside is the bruises after a good day, still have mine from New year`s day sail and day after(15-20knots). Mast fell down on 1 January (a tradition for me,twice in 3 years so far), and went pitchpoling on 2nd.
Air temp was 38-40deg C, no real need for a wetsuit !
My greatest fear is sailing in less than 4knots, and even worse, racing. I believe catamarans are essentially monohulls, if it has one hull in the water it`s all good. Other one needs to be kept dry !!