If preheat temps were monitored and maintained then you wouldn't have an issue. That would be correcting the issue. Regarding the questions you've asked, the answers would vary depending on the type of electrode/welding process and material type. For some combinations, no, not much of an issue. In others, yes, it would be a big deal. If your preheating and maintaining temps then you covered your bases. It's the "maintaining" part that gets lost in the shuffle. If that 5 degree day with wind chill at -15 or -20 was causing your material temps to fall below any required preheat temp between passes then you haven't maintained anything. This could lead to a problem yes. That's why there are certain products to help with this issue, like induction blankets when torches can't offset the issues on a job or wraps used to protect a completed weld from cooling to fast from....maybe wind, or having people assigned to help the welder running torches/grinders. Anyway, my point was wind isn't just about porosity. If you utilize preheat when necessary and preheat maintenance then you've got it under control. Welded things tend to break on occasion, sometimes it's because things weren't done as well as they should have been.

I've attached a picture. Weld was made of the same material, same welding process and procedure. Picture on the left was cooled by wind where weld preheat temp was not maintained. There were eight welds made, none protected from wind allowing temps to fall below requirements. Welds were cut out and replaced using exact same procedure but also wind shields. Eight straps in the noncompliant welds all failed as specimen on the left. A verification weld was cut out and all 16 specimens were as the same as the specimen on the right. The failed area shown is not porosity, as the picture might indicate, but hydrogen embrittlement commonly know as "fisheyes"....Base material has a 90K tensile, 70K yield welded with low hydrogen process.

I wasn’t going to go there, but Al opened the door.  I was on the bus the other day and I had one of those attacks.  The music was really loud, but I managed to time my excessive wind with the beat.  After four or five songs I started feeling better.  As I left the bus, people were really giving me the evil eye.  That’s when I remembered that I’d been listening to my iPod.  It’s not really my fault.  I've been diagnosed with excessive wind, but like everybody else who has a severe medical condition, I'm not going to suffer in silence.  When I was a kid, I remember trying the trick where you light one on fire.  We weren’t allowed to play with lighters, so I used a candle.  The Priest didn't find it as funny as I did, and everybody just sat there looking at me in disgust.  One lady in the front row even told me to pull my pants up.  A few years later, a bunch of us were in a crowded, but it was a quiet room.  Me being me, I decided to initiate another round of excessive wind.  All of a sudden, the quietness in the room turned into laughter.  One of my friends approached me about 30 minutes later, saying how it was the funniest thing he’d ever seen.  My wife however, said that it ruined our wedding.  I’m good at it, but I can’t hold a candle to my wife, and I wouldn’t want to.  Remember putting a blade of grass in between your thumbs, blowing it, and hearing the weird sounds it made? Same thing happens when my wife wears thongs.  Don’t get me wrong.  Her excessive wind outbursts are not all that frequent because she can’t keep her mouth shut long enough to build up any pressure.  When it finally does happen, I’m not saying it’s loud, but she'll never get hit by a ship.