A fog advisory was issued for the second day in a row Wednesday evening with unseasonably mild weather dominating the Christmas break.
After Rudolph had to guide Santa's sleigh through fog Christmas Eve, Environment Canada posted another advisory for Christmas night into Boxing Day.
A number of areas including Sarnia-Lambton, Huron-Perth, and London-Middlesex are included.
The Environment Ministry said fog will develop, become widespread and dense in some areas by midnight, and persist into the middle of Thursday morning.
The weather agency warned that fog patches over some parts of the region may cause reduced visibility, and that travel may become hazardous in areas of near zero visibility.
Motorists were advised to turn on lights and maintain a safe following distance.
The high temperature at Sarnia's Chris Hadfield Airport reached about 7 C, 45 F Christmas Day, near the record of 7.3 C set in 2015. A high of 11 C, 52 F was forecast for Boxing Day with the record for December 26 at 7 C in 2014.
Temperatures above normal for this time of year were expected to continue through the weekend with a seasonal high of -1 C, 30 F by the last day of 2019 on Tuesday.