For those going tonight: Capital Weather Gang has 'Clouds may be on the increase, but the game should stay dry. Consider bringing a jacket for the last innings of the game, when 60s (without sun) could feel a tad cool.' with 5% chance of precip.
If you use Metro's Red line betwen Rhode Island Avenue and Silver Spring - heavy trackwork starting at 22.00 (
http://www.wmata.com/rider_tools/metro_service_status/advisories.cfm?AID=1022 - includes station closures and shuttle buses replacing trains over that sector).