Environment Canada has issued a frost advisory for Ottawa, Gatineau and parts of eastern Ontario.
While the forecast high for Thursday is 21°C, the temperature is expected to plunge rapidly in the late afternoon and evening, dropping to a low of 0°C overnight.
Environment Canada blames an Arctic high pressure area for the rapid cool-off.
“Cover up plants, especially those in frost-prone areas,” the advisory says.
Frost advisories are issued whenever a risk of frost is possible during growing season, which could lead to damage or destruction to plants and crops.
The advisory is in effect for the following areas: Gatineau, Tamworth - Sydenham - South Frontenac, Stirling - Tweed - Madoc, Merrickville-Wolford - Kemptville, Westport - Charleston Lake, Brockville - Prescott, Gananoque - Mallorytown, Maxville - Alexandria, Cornwall - Lancaster, Winchester - Newington, Morrisburg - Long Sault, Prescott and Russell, Smiths Falls - Perth - Eastern Lanark County, Plevna - Sharbot Lake - Western Lanark County, Ottawa North - Kanata - Orléans, Ottawa South - Richmond - Metcalfe