Environment Canada issued a yellow frost advisory early Monday morning for York and Durham regions, Hamilton, Caledon and Halton Hills. The frost is expected to continue overnight and into Tuesday morning with damage to plants, trees and crops possible.
Toronto and the rest of the GTA were not included in the advisory, but could see a risk of frost overnight with lows between 1 C and 3 C. Monday's high will be 13 C, as highs in the low double digits will last through Thursday before a forecast high of 19 degrees on Friday.
The extended forecast shows Tuesday's high of 14 C with scattered showers, followed by Wednesday's high of 16 C with thunderstorms and hail. Thursday will see partly cloudy conditions with a high of 16 C.
Below seasonal temperatures continue across the region, but they are set to improve by the long weekend. Early forecasts for the long weekend predict warm temperatures, with highs in the 20s and some showers possible.