Nearly three-quarters of an inch of rain had fallen there as of 3 p.m. central time, and as much as another half inch of rain is possible through Monday night, according to the National Weather Service's Kansas City forecast office.
Game 3 is now set for 8 p.m. Tuesday, with Game 4 at 4 p.m. Wednesday and Game 5, if necessary, at 4 p.m. Thursday. The best-of-seven series, which the Royals lead, 2-0, was slated to return to Baltimore on Friday, if necessary.
A wet, stormy system is moving through the nation's midsection, bringing severe weather and flash flooding concerns in the lower Mississippi River valley.
As Royals fans planned to welcome their team, baseball officials were tempering their expectations as early as Sunday.
"It doesn't look good, they say," Royals manager Ned Yost said in a post on the team's website Sunday. "You can't see it yet on the radar, but it's supposed to come over the Rockies and blow up. We might have two or three inches [of rain], but it's supposed to be good for Tuesday."
Weather is not forecast to affect the series going forward. Rain is expected to clear out of Kansas City by midday Wednesday, with sunny skies and seasonable temperatures through the rest of the week.
If the series returns to Baltimore this weekend, pleasant weather is also in the forecast.
Baltimore Sun reporter Eduardo A. Encina contributed to this report.