In April and May the wind often comes off Lake Michigan (less than a mile to the east), which means a northeast wind "blowing in" to knock down potential home runs and turn them into outs. In the summer, however, or on any warm and breezy day, the wind often comes from the south and the southwest, which means the wind is "blowing out" and has the potential to turn normally harmless fly balls into home runs. A third variety is the cross-wind, which typically runs from the left field corner to the right field corner and causes all sorts of interesting havoc. Depending on the direction of the wind, Wrigley can either be one of the friendliest parks in the major leagues for pitchers or among the worst. This makes Wrigley one of the most unpredictable parks in the Major Leagues.
Many Cubs fans check their nearest flag before heading to the park on game days for an indication of what the game might be like; this is less of a factor for night games, however, because the wind does not blow as hard after the sun goes down.
With the wind blowing in, pitchers can dominate, and no-hitters have been tossed from time to time, though none recently; the last two occurred near the beginning and the end of the 1972 season, by Burt Hooton and Milt Pappas respectively. In the seventh inning of Ken Holtzman's first no-hitter, on August 19, 1969, Hank Aaron of the Atlanta Braves hammered one that looked like it was headed for Waveland, but the wind caught it just enough for left fielder Billy Williams to leap up and snare it in "the basket".
With the wind blowing out, some true tape-measure home runs have been hit by well-muscled batters. Sammy Sosa and Dave "Kong" Kingman broke windows in the apartment buildings across Waveland Ave. several times. Glenallen Hill put one on a rooftop. Batters have occasionally slugged it into, or to the side of, the first row or two of the "upper deck" of the center field bleachers. Sosa hit the roof of the center field camera booth on the fly during the NLCS against the Florida Marlins, some 450 feet away.
But the longest blast was probably hit by Dave Kingman on a very windy day in 1976 while with the Mets. According to local legend, that day, Kingman launched a bomb that landed on the third porch roof on the east (center field) side of Kenmore Avenue, some 550 feet away.
No batter has ever hit the center field scoreboard, however it has been hit by a different kind of ball: a
golf ball, hit by Sam Snead, using a two iron.[7]
No matter the weather, many fans congregate during batting practice and games on Waveland Avenue, behind left field, and Sheffield Avenue, behind right field, for a chance to catch a home run ball.