Stouffville, Ontario is set to kick off the week with sunny skies and rising temperatures that will feel well above normal for early June, according to Environment Canada. The hot and humid conditions are expected to stick around through Thursday, with a risk of thunderstorms moving in by Tuesday afternoon.
Monday will be sunny with a high of 26°C, but humidity will make it feel closer to 27. The UV index is forecast to reach 9, which is considered very high, so anyone heading outdoors should use sunscreen, wear a hat, and seek shade during peak afternoon hours.
Tuesday starts off sunny as well, but clouds will build through the morning. Environment Canada says there is a 40 percent chance of showers in the afternoon, along with a risk of thunderstorms. Winds are expected to pick up from the southwest at 20 km/h, and humidex values could climb to 34 as the temperature reaches 29°C.
While these temperatures are above the seasonal norm of 23°C, they have not yet triggered a formal heat warning. Under the Harmonized Heat Warning and Information System for Ontario (HWIS), warnings for southern Ontario are issued when daytime highs hit at least 31°C and overnight lows stay at or above 20°C, or when humidex values reach 40 or higher, for two consecutive days.
York Region Public Health reminds residents that extreme heat can affect anyone, but seniors, infants, people with chronic health conditions, outdoor workers, and those taking certain medications are at greater risk. The health unit advises everyone to drink plenty of water, stay in cool places, and check on vulnerable neighbours during hot spells.
The combination of heat and potential thunderstorms later in the week means residents should keep an eye on the sky and have a plan to get indoors quickly if storms develop. Environment Canada notes that southern Ontario is one of the most thunderstorm-prone areas in the country, and severe storms can bring dangerous lightning, strong winds, and heavy downpours.
Looking further ahead, the long-term forecast shows the hot pattern continuing, with temperatures climbing to 30°C by Thursday. Residents are encouraged to plan outdoor activities for the mornings early in the week, before the peak heat and storm risk settle in.
