Cold air and clear skies left over from Tuesday's winter storm system will mean frosty morning lows on Thursday. A Frost Advisory is in effect from 2:00 AM to 9:00 AM Thursday across the San Joaquin Valley. Lows will range from 29 to 34-degrees for up to 7 hours. A gradual warming trend is expected through this weekend. There will be a slight chance of precipitation on Saturday.