London-area residents hoping for perfect weather over the Civic Holiday long weekend may need to keep their umbrellas handy. According to Reta Ismail, a pair of low-pressure systems are expected to bring increasing cloud cover, showers and the risk of thunderstorms across southwestern Ontario through much of the weekend. “We had high pressure in play today and it was absolutely beautiful. Not a cloud in sight,” Ismail said. “But heading into the weekend, we are tracking two low-pressure systems that do threaten our outdoor activity.” Friday remains the pick of the weekend, with sunny skies, a high of 26 C and only a light southerly breeze. Conditions are expected to change Saturday as the first weather system moves through the region, bringing more cloud cover and the possibility of scattered light showers and isolated thunderstorms. “Saturday will be mostly cloudy, climbing to a high of 28 degrees,” said Ismail. “That storm risk is there because of the humidity in the air mass.” While much of the London area is expected to stay relatively dry for parts of Saturday, forecasters are watching a stronger storm system developing south of the border that could have a greater impact on the region Sunday. According to Ismail, the greatest risk for heavy rain and thunderstorms arrives Sunday morning and could intensify throughout the day. “Sunday morning we could see those heavier downpours and, of course, thunderstorms, especially along the shores of Lake Erie,” she said. “Then later in the day, becoming more widespread, you could see through Windsor into London.” By Sunday afternoon, stronger thunderstorms could develop across southwestern Ontario, potentially bringing periods of heavy rainfall. Despite the unsettled conditions, temperatures are expected to remain seasonable through the weekend. “Sunday, the temperature is right where it’s supposed to be, but you will need your umbrella this long weekend,” Ismail said. Holiday Monday currently looks to be the driest day of the long weekend, with a high near 26 C and a mix of sun and cloud. The pleasant weather is expected to continue into Tuesday, with temperatures reaching 28 C under mostly sunny skies.
