It is recommended that you reduce strenuous activities today in southern Manitoba due to high humidity. Humidex values will be near 40, making it feel very uncomfortable. I personally am issuing a high humidity warning for the RRV for today, as a result.
All this heat and humidity will clash with a front moving east today. Thunderstorms are likely for most of south-central and southeast Manitoba later this afternoon, and early/mid evening. Keep an eye on the sky! Some of these storms could be quite severe, thanks to extreme instability, moderate shear, high moisture and a trigger. The main threats will be large hail (golf ball to tennis ball sized), flooding rains due to the slow moving nature of the storms, damaging winds, frequent lightning and an isolated tornado.