A ridge of high pressure settling in over Ontario will allow clear skies and light winds to develop over much of Northern Ontario tonight. As a result, temperatures will drop to the freezing mark and frost will develop overnight into Friday morning. Areas directly adjacent to Lake Superior and the north channel may remain frost free.
As the ridge moves eastward, temperatures will recover slightly for areas west and north of Lake Superior tomorrow. However, frost warnings will likely continue for Northeastern Ontario Friday night into Saturday morning.