How much wind is too much...

In the outback? What is the no go for sustained wind?

What water? 10-12 mph or so in the salt isn't pleasant but is doable. More than that I'd stay home.

Ocean... Westport, Neah Bay, the strait.

Depends how long you are able to grind against the wind..... 12-15 starts to get uncomfortable. 25 really sucks and starts to get unsafe. Depends on swell, current, wind direction too....

I have a cooler and a tackle box strapped behind the seat of my 13" Revolution.  When  the wind is coming from behind me, this gear can catch the wind, overpower the standard rudder on the Revolution, and turn me in a direction I don't want to go, which is pretty irritating.  It could also be dangerous, if the inability of the standard rudder to handle the wind keeps me from going where I need to go.  I could use my paddle as a second rudder, but that is inconvenient.  I'm going to get a sailing rudder, and hope that reduces the problem.

I feel more comfortable in wind when I'm in a paddle kayak, because I can keep the kayak going where I want it to go, because I can brace into big breaking waves, and because I can clip in my thigh straps if the waves get sufficiently boisterous.

IMHO installing the sailing rudder is akin to the turbo fin upgrade......the improvement is immediate....for me, the sailing rudder change over on my Outback was to improve tracking when using my down rigger...even with wind the tracking is excellent.

I recently installed the new/larger rudder on my PA-14 and although I did not have a tracking problem with my down rigger, the larger rudder does improve tracking 

I was out at hoe buck wednesday, thursday, and friday this last week. Coming back from the rock on wednesday at 20:00 if I would have had to paddle i would have been sol, it was 15 mph offshore with gusts up to 25. Being slapped by a 2 to 3 ft wind wave every 4 seconds makes for a really long peddle. With sustained winds on the ocean, its not like you can just take a break. The wind will put you behind where you started and going into shore will mess you up in the surf.
That being said, if you need to fish you can always use the wind for your drift, kind of like you do when you use the tide.  Park one car at the top and one at the bottom, of course this is assuming you're on the strait and the winds cooperate.