Cold Arctic air continues to dominate the weather across Ontario.
There's the risk of frost or freeze conditions for Sarnia-Lambton again Monday and Tuesday nights.
Environment Canada is forecasting a low of minus four Monday night into Tuesday morning.
Preventative measures should be taken to protect frost-sensitive plants and trees.
Temperatures near the seasonal high of 20 C for this time of year in Sarnia are expected by Friday.
A polar vortex that pulled very cold air down from the north has caused record cold temperatures across the region.
May 8 for example, was unofficially the coldest in Sarnia since 1983.
