Before you read this, please read the following disclaimer:
I have put together this information from schedules that have already been publicly posted. I am reasonably certain that it is correct, but I cannot and will not vouch for any errors or changes that are made in it.
That said, here's why I'm posting this today:
The Cubs generally release their schedule for the following season later than most other teams. I've never quite been able to figure out why, because if one team puts theirs out, it's clear to me that the entire schedule is finished. In my opinion, there's no reason that MLB shouldn't mandate that all clubs release their next-year's schedules on their last home date.
I actually had fun doing this -- it's sort of like an acrostic puzzle; you fill in the blanks based on what things cannot be, and once you have eliminated all the "can't be" possibilities, you're left with obvious choices. Example: for April 7-8-9, all fourteen other NL teams are accounted for by the schedules that have already been made public, so the Cubs must be playing the Cardinals -- and since we also know that the Cardinals' first home date is April 10 vs. Milwaukee, that means that the April 7-8-9 Cub/Cardinal series will be the home opening series at Wrigley Field.
The following teams that the Cubs are playing in 2006 have already posted their schedules: Reds, Dodgers, Marlins, Brewers, Diamondbacks, Padres, Giants, Nationals, Astros, Rockies and Phillies, and also the AL interleague opponents: White Sox, Tigers, Indians and Twins.
I'm reasonably certain that this is it -- the only sets of series that MIGHT be different are the two Atlanta series (those might flip-flop from what I have, home in May, road in September), and the two late-season Pirate series; the one in August might be a home series, and the September one a road series, although that would make the # of home/road dates not match up. Right now (and I know you'll count them too) there are 81 of each.
All times CDT
April 3, 5 at Cincinnati (1:10, 11:35)
April 7-8-9 St. Louis (1:20, 1:20, 7:05)
April 11-12-13 Cincinnati (1:20, 1:20, 1:20)
April 14-15-16 at Pittsburgh (6:05, 6:05, 12:35)
April 17-18-19 at Los Angeles (9:10, 9:10, 9:10)
April 21-22-23 at St. Louis (7:10, 1:15, 1:15)
April 24-25-26 Florida (6:05, 7:05, 1:20)
April 28-29-30 Milwaukee (1:20, 1:20, 7:05)
May 1-2 Pittsburgh (7:05, 1:20)
May 3-4 at Arizona (8:40, 8:40)
May 5-6-7-8 at San Diego (9:05, 9:05, 3:05, 9:05)
May 9-10-11 at San Francisco (9:15, 9:15, 2:35)
May 12-13-14 San Diego (1:20, 1:20, 1:20)
May 16-17-18 Washington (7:05, 7:05, 1:20)
May 19-20-21 at White Sox (3:05, 12:20, 3:05)
May 22-23-24 at Florida (6:05, 6:05, 12:05)
May 26-27-28 Atlanta (1:20, 12:20, 1:20)
May 29-30-31 Cincinnati (1:20, 7:05, 7:05)
June 2-3-4 at St. Louis (7:10, 3:05, 1:15)
June 5-6-7 at Houston (7:05, 7:05, 1:05)
June 8-9-10-11 at Cincinnati (6:10, 6:10, 5:10, 12:15)
June 13-14-15 Houston (7:05, 7:05, 1:20)
June 16-17-18 Detroit (1:20, 3:05, 1:20)
June 19-20-21 at Cleveland (6:05, 6:05, 6:05)
June 23-24-25 at Minnesota (7:10, 6:10, 1:10)
June 26-27-28-29 Milwaukee (7:05, 7:05, 1:20, 1:20)
June 30, July 1-2 White Sox (1:20, 12:20, 1:20)
July 3-4-5 at Houston (7:05, 1:05, 7:05)
July 6-7-8-9 at Milwaukee (7:05, 7:05, 6:05, 1:05)
July 10-11-12 all-star break
July 14-15-16 New York (1:20, 3:05, 5:05)
July 18-19-20 Houston (7:05, 7:05, 1:20)
July 21-22-23 at Washington (6:05, 12:20, 12:05)
July 24-25-26 at New York (6:10, 6:10, 12:10)
July 27-28-29-30 St. Louis (7:05, 1:20, 3:05, 1:20)
July 31-Aug. 1-2-3 Arizona (7:05, 7:05, 7:05, 1:20)
August 4-5-6 Pittsburgh (1:20, 3:05, 1:20)
August 8-9-10 at Milwaukee (7:05, 7:05, 1:05)
August 11-12-13 at Colorado (8:05, 7:05, 2:05)
August 14-15-16 at Houston (7:05, 7:05, 1:05)
August 18-19-20 St. Louis (1:20, 12:20, 1:20)
August 21-22-23-24 Philadelphia (7:05, 7:05, 7:05, 1:20)
August 25-26-27 at St. Louis (7:10, 12:20, TBA)
August 28-29-30 at Pittsburgh (6:05, 6:05, 11:35)
Sept 1-2-3 San Francisco (1:20, 1:20, 1:20)
Sept 4-5-6-7 Pittsburgh (1:20, 7:05, 7:05, 1:20)
Sept 8-9-10-11 at Atlanta (6:35, 6:05, TBA, 6:35)
Sept 12-13-14 Los Angeles (7:05, 7:05, 1:20)
Sept 15-16-17 Cincinnati (1:20, 3:05, 1:20)
Sept 18-19-20 at Philadelphia (6:05, 6:05, 6:05)
Sept 22-23-24-25 at Cincinnati (6:10, 5:10, 12:15)
Sept 26-27 Milwaukee (7:05, 7:05)
Sept 29-30-Oct 1 Colorado (1:20, 3:05, 1:20)
UPDATE [2005-10-3 13:07:21 by Al]: Have realized there were a few errors, which I've changed above: the Pittsburgh series in April should be a home series, and the one in May a two-game road series; Atlanta is at Wrigley Field in May; the Cubs are in St. Louis for four in June and only three in April; and the two Pittsburgh series did indeed flip-flop in August & September. I still think the two St. Louis series might switch in August, but that would make a 12-game monster road trip, so it's likely to stay the way it is, even though that indicates a three-game weekend trip to St. Louis.
UPDATE [2005-10-3 16:54:50 by Al]: Had it right the first time: the Pirates released their schedule today. The Cubs are indeed at Pittsburgh in April, home for the two-game set in May, at Pittsburgh in late August (dates slightly changed), and home for a four-game series starting on Labor Day. Adjustments made above.
UPDATE [2005-10-7 20:07:28 by Al]: One more change -- it was pointed out to me that the Rockies, who I had in Chicago for a four-game series to end the season, are scheduled at home on the first of those dates. I have adjusted that to a three-game series, and it is likely that the extra game will make a four-game, post-All Star break series with the Mets. This also makes an even number of games with both the NL East and NL West.
UPDATE [2005-10-15 20:43:44 by Al]: The Mets released their schedule -- and it shows only a three-game series at Wrigley Field after the All-Star break. Thus, there must be one other home date attributable to either the Cardinals or Braves. It can't be the Braves, because that would have the Cubs playing far more than 20 consecutive days. Thus, I'm thinking it could be a four-game opening series vs. the Cardinals, wrapping around to Monday, April 10. That's how I'm going to post it for now.
UPDATE [2005-10-24 16:27:20 by Al]: The Braves released their schedule today -- that leaves only the Cubs and Cardinals as NL teams that haven't, so that confirms that the additional date must be for the Cardinals, because the Cubs are playing four games in Atlanta in September, not three.
UPDATE [2006-1-9 9:35:30 by Al]: The Cubs released some game time changes today; they are listed below, and also changed in the list above:
April 9, St. Louis: 7:05 (first Sunday home game!)
April 30, Milwaukee: 7:05
May 20, at White Sox: 12:20
May 27, Atlanta: 12:20
June 3, at St. Louis: 3:05
June 17, Detroit: 3:05
July 1, White Sox: 12:20
July 15, New York: 12:20
July 16, New York: 5:05 (odd time)
July 22, at Washington: 12:20
July 29, St. Louis: 3:05
August 5, Pittsburgh: 3:05
August 19, St. Louis: 12:20
August 26, at St. Louis: 12:20
September 2, San Francisco: 1:20
September 16, Cincinnati: 3:05
September 30, Colorado: 3:05
August 27 at St. Louis, originally listed as 1:15, is now TBA -- this is a game that could wind up on ESPN on Sunday night; also, another Sunday, September 10 at Atlanta, originally listed as 12:05, is also TBA.