The start of the last week of May is going to feel a bit more like the middle of July in southwestern Ontario.
Environment Canada has issued a heat warning for the region, including London and Middlesex County, Elgin County, Oxford County, Chatham-Kent, Windsor and Essex County, Sarnia-Lambton, Huron County, and Perth County.
The weather agency said it expects daily high temperatures will hit 30 C on Monday, Tuesday, and Wednesday. Factoring in humidity, it will feel more like the mid-to-upper 30s.
"We started off the month really, really cold and now there is a surge of warm air. It is coming from the Gulf of Mexico and that is why we are looking at temperatures reaching into the 30s and a humidex quite close to 40 C," said Gerald Cheng, warning preparedness meteorologist at Environment Canada.
The average daytime high for this time of year is 20.9 C, nearly ten degrees lower than those forecast for the start of the week.
The sweltering heat and humidity could lead to some unsettled weather and poses an elevated risk of heat illnesses, such as heat stroke or heat exhaustion.
"The warm air mass raises the possibility of some thundershowers," warned Cheng. "As this is our first round of very warm weather, keep in mind that some of the measures that we usually take like going to a shopping mall to cool down may not be available because of physical distancing measures. So we will have to find other ways to stay cool... If you have elderly neighbours, check on them."
Anyone spending time outdoors is advised to drink plenty of fluids and try to take frequent breaks in a cool place. People are also being reminded to never leave pets in a vehicle when the weather is this hot.
There is a possibility some temperature records could fall across the region, particularly in London where the record high for May 25 stands at 28.3 C set back in 1975.
The scorching conditions will be short-lived though, with more seasonable temperatures returning on Thursday when the high is expected to be 25 C.
"It is really just for three days and after that temperatures will slowly come back down," said Cheng. "Looking at the long-range it seems like we are going to end the month with more seasonal temperatures. So we won't see these 30 C days again in May."