Nearly all of southern Manitoba remains under a heat warning Monday morning, and parts of east-central Manitoba are as well.

"Southerly winds are spreading hot and humid weather into Manitoba," Environment Canada says in the warning. "Over the coming days, daytime highs will climb into the low thirties with overnight lows staying in the upper teens or low twenties. Humidex values will be in the upper thirties or low forties."

Environment Canada says daytime highs will remain in the high 20s and low 30s throughout the week for the City of Winnipeg. They also say it's important to watch at-risk people during the heatwave.

"The risks are greater for young children, pregnant women, older adults, people with chronic illnesses and people working or exercising outdoors. Drink plenty of water even before you feel thirsty and stay in a cool place. Check on older family, friends and neighbours. Make sure they are cool and drinking water."

Signs of heat-related illness include: dizziness/fainting; nausea/vomiting; rapid breathing and heartbeat; extreme thirst; decreased urination with unusually dark urine.