Summer kicks off with sun, but that won't last

Summer’s kicking off in grand fashion Thursday with sunny skies and fine temperatures, but it doesn’t look like it’ll last long.
Clouds are expected to roll in Thursday afternoon, and showers could ensue this evening and overnight.
Thursday’s high is expected to be about 24 C, with a humidex equivalence of 26 and UV index 9 or very high.
Overnight expect showers, with possible thunderstorms, with five to 10 mm of rain. The low is forecast at 18.
The showers and T-storms a