Capital Weather Gang's NatCast has: 'Sunday night baseball just a tad on the cool side. A jacket is advisable, especially for the later innings', temperatures in mid-60's at first pitch, low 60's by ninth inning, 10% chance of rain.
MORE IMPORTANT THOUGH FOR THOSE WHO USE METRO:
This is the final full day of the major track-work - and apparently there has also been no change in the plans not to add extra trains if the match runs late - at least we haven't gotten any E-mails from the Nats indicating any changes, and nothing on the Metro site indicating same either.
Last trains tonight, per Metro site:
FROM NAVY YARD:
Northbound (to Greenbelt): 23.39 [site warns 'Red line transfer not possible']
Southbound (to Branch Avenue): 00.17
FROM GALLERY PLACE
Red Line eastbound (to Glenmont): 00.08
Red Line westbound (to Shady Grove): 00.02
FROM L'ENFANT PLAZA
Blue line eastbound (to Largo): 00.11
Orange line eastbound (to New Carrollton): 00.11
Orange line westbound (to Vienna): 23.59
Yellow line southbound (to Huntington): exactly midnight
FROM ARCHIVES [a favourite alternative of mine for post-baseball Yelloe Line transfers]
Yellow line southbound (to Huntington): 23.58
Full list of Metrorail stations (click a station to find out last trains from that station): http://www.wmata.com/rail/stations.cfm
Bear in mind, too, that trains don't run as often Sundays to begin with - one may want to budget a bit more time getting there/back as it is.