The humidex soared to 40 C Wednesday afternoon making it likely the hottest day of the season so far in Sarnia-Lambton.
Environment Canada's heat warning remains in effect with the temperature in the low 30s, and a severe thunderstorm watch was issued over the noon hour and upgraded to a warning just before 5 p.m.
More showers and thunderstorms were expected Wednesday afternoon and night in advance of a sharp cold front that will bring a stretch of very nice weather into early next week.
The weather agency said Sarnia-Lambton likely saw 20 millimetres to 30 millimetres of rain and wind gusts during the storm.
The severe thunderstorm warning was ended for the region shortly after 8 p.m.
