It's been very windy here the past 2 seasons. Sometimes the umps have told us they wouldn't be calling any infield flys called as there wouldn't be any routine popups due to the wind. A few times they've widened the strike zone a little to help the pitchers. Last year on opening day, the wind was blowing in at around 30 mph. Batter hit what should have been a routine fly to mid-centerfield, but our pitcher caught it between the rubber and 2nd base.
The worst conditions I've seen were in a tournament championship game years ago. Two pitchers on the other team kept rotating every 2 to 3 hitters because they were so frustrated that they couldn't throw strikes in a dust storm. Oddly, our pitcher threw a knuckleball and had few problems with the wind. The day before, we took batting practice before our first game when it was so foggy we couldn't see the hitter or ball from the outfield.