Frost possible tonight

High pressure will crest over eastern Ontario tonight and provide widespread frost in many region of the east and south and into southern and western Quebec. You are advised to protect tender growing items. It will be sunny and mild Friday (21C) before a stubborn low pressure area moves in for the weekend. While it will not be a washout, many regions will be chilly and damp all weekend. Monday should be sunny and warmer.

Frost Warning in effect...
http://www.weatheroffice.gc.ca/warnings/report_e.html?on13