OTTAWA -- The heat warning for Ottawa-Gatineau and eastern Ontario persists Sunday, with muggy conditions all day and overnight.

Sunday's forecast calls for a few clouds and a high of 33°C°C. The forecast humidex is 42. The UV index is 9, or very high. There is a 30 per cent chance of showers and the risk of a thunderstorm in the afternoon.

Environment Canada's heat warning for the region says nighttime will bring little relief, with lows in the low- to mid-20s. The overnight low heading into Monday morning is a stuffy 22°C.

Hot, humid conditions continue Monday with a high of 30°C and a humidex of 40. Monday's forecast includes a 70 per cent chance of showers in the afternoon.

By Tuesday, cooler air is expected to arrive. The high for Tuesday is 28°C, with sun/cloud mix and a 40 per cent chance of showers.

Staying cool during the heat wave

  • Ottawa Public Health offers tips to stay cool during the heat wave
  • Drink plenty of water and avoid alcohol and caffeine
  • Avoid heavy outdoor activity
  • Wear a hat, light and loose-fitting clothing, sunscreen and sunglasses when outside
  • Bring an umbrella and water when you leave home
  • Cool off in an air-conditioned space
  • Cool off in the shade or at a park or greenspace
  • Use a fan and mist your skin with water
  • ake cool baths and showers as often as needed
  • Keep your home cool by closing blinds and curtains on any windows facing the sun