The 90th annual lighting of the National Christmas Tree is tonight.

Coming up today in the D.C. region:

National Christmas Tree: The 90th annual National Christmas Tree Lighting Ceremony will be held today at 4:30 p.m. at the White House. The festive holiday event is expected to tie up traffic for D.C. commuters.

Silver Line: Metro is expected to release a report on changes to the Silver Line, including a decision to extend the rail line.

Gay marriage: Gay couples planning to wed Jan. 1 will be able to get post-dated marriage licenses today in some Maryland counties, officials said.

Weekend plans: The Going Out Gurus will discuss concerts, happy hours, weekend getaways and other weekend plans in a live chat at 1 p.m.