KITCHENER -- After a rainy start to the week conditions are forecast to clear, but as temperatures remain cool the risk of frost returns for parts of southwestern Ontario.

Environment Canada has issued frost advisories for various parts of the region, including Oxford, Brant and Norfolk counties, as patchy frost is expected overnight and early Thursday morning, returning again Friday morning.

Cool, calm and clear

Are conditions favourable for frost to occur in your area? If so, you might be wondering why there’s no frost advisory in place.

Environment Canada issues public weather alerts based on a specific criteria, and that criteria will change for different locations.

EC issues Frost Advisories when temperatures are expected to reach the freezing mark during the growing season, leading to potential damage and destruction to plants and crops.

EC shared a tweet explaining the dates in which advisories will be sent out for each region in the province.

“New for this summer, we’ve changed the dates of our frost season across much of Ontario. These images show the first date we will issue a Frost Advisory ( if frost is forecast ) for your region,” the service said in the tweet.

For Waterloo Region, that means Frost Advisories will start being issued on May 7, if and when frost is forecast.