A couple of inches of rain or more could fall between this evening and Wednesday afternoon.
The Phillies might luck out for this evening's 7:05 game against the Houston Astros, with the heaviest rain expected after midnight.
"There may be delays, but the game shouldn't be called," said meteorologist Tony Gigi of the National Weather Service.
More of a worry is Tuesday's 1:05 p.m. game, second of two against Houston at Citizens Bank Park. Heavy rain is possible morning and afternoon, and thunderstorms could make an appearance.
If it were an evening game, the prospects would be better, Gigi said.
Tuesday morning's commute could also get sloppy. Although no flood watch has been issued, poorly drained low-lying streets might see some ponding problems, Gigi said.
If the system is slow to arrive, then the Tuesday afternoon commute might be more affected.
A secondary system could bring more light rain on Wednesday, when the Phils will be in Chicago.
"Come Wednesday night through the end of the weekend, it looks dry and pleasant," Gigi said.
Highs through Sunday after expected to be in the 70s, with lows from the mid 50s to low 60s.
For more on the forecast, go to Philly.com's weather page.