Your midday New Jersey weather update A Frost Advisory is in effect across much of New Jersey this morning, with temperatures dropping as low as 35 degrees in sheltered valleys. If you've already started planting tender vegetables or flowers, you'll want to take action to protect them from potential frost damage, especially in rural and valley locations where cold air settles overnight. This Sunday morning starts chilly with temperatures around 45 degrees at 4 A.M., but we'll see steady warming through the day.