10:30 a.m. update: Frost advisories and freeze warnings have been posted for most areas north and west of D.C. with chilly temperatures on the way for tonight. The frost advisory is in effect from midnight to 9 a.m. Monday and includes Howard, Montgomery, Loudoun, Prince William and Fauquier counties. The freeze warning covers points further north and west including Carroll and Frederick counties and is also in effect from midnight to 9 a.m. Monday.