Just a few minutes ago, a report came through on Twitter for tonight's game:
Tonight’s @brewers-@cubs game at Wrigley Field postponed due to forecast of rain and sub-freezing wind chills throughout the night.— MLB (@MLB) April 10, 2013
This isn't a surprise, as yesterday the weather forecast called for rain throughout the day today in Chicago, and with the wind chills as low as they are, postponing the game became an obvious decision.
Adam McCalvy notes that no make up date has been announced. Looking at the schedule, the Brewers have two more series in Chicago this year: July 29-31 and September 6-8. The Brewers and Cubs have a mutual off day on September 5, which is the only off day they both have around either of these series.
Adam McCalvy also points that Kyle Lohse will be moved back to Friday, and will start against his former team in St. Louis.
Edit: Mike Vassalo has the starting pitchers for the series in St. Louis. Kyle Lohse will start Friday, followed be Yovani Gallardo and Marco Estrada. One thing to note here is that Mike Fiers is not listed on this rotation, so the Brewers will be keeping him in the bullpen for now.
Edit 2: Vermont Cubs Fan found that the game has been rescheduled for July 30 as part of a day-night doubleheader. The Brewers official Twitter account also confirms this:
#Brewers Cubs make-up date: Tuesday, July 30 at 1:20 p.m. as part of a Day-Night Doubleheader.— Milwaukee Brewers (@Brewers) April 10, 2013