It'll be a slow and damp transition from spring to summer.
The start of summer officially starts on Sunday at 11:31 p.m.
Environment Canada is calling for a chance of showers to start in the evening and continue through Monday.
"Following that rain, into the early week, it is looking like a bit of a cool down, unfortunately. So it may be a bit of a depressing beginning to the summer," said Warning Preparedness Meteorologist Steven Flisfeder.
However, residents will not have to wait long for typical summer weather as warmer temperatures and sunshine is expected later in the week.
Flisfeder said over the course of summer there will be some "up and down" temperatures in the forecast but overall, above seasonal temperatures are expected.
"In general, temperatures will be in the mid to high 20s but of course it's going to be different day to day," he said. "So there could be some days where we see temperatures into the low to mid-30s with humidex values approaching 40."
In terms of precipitation, Flisfeder said that's a little tougher to predict.
"It's a little difficult to say if we'll see an increase in thunderstorm activity this year in general but certainly the warmer temperatures will aid in the formation of those thunderstorms," he said.
Precipitation levels during the spring have fluctuated over the past few months but Flisfeder said southwestern Ontario did have above seasonal temperatures overall.
"Precipitation is a bit of a different story. March and April were a little bit closer to average but then [in] May and early June we saw some fairly significant deficits in precipitation amounts, particularly through May," he said.
With warmer weather approaching, Flisfeder said it's important for residents to take steps in protecting themselves from the heat, which includes drinking plenty of water and applying sunscreen when outdoors.