Children play in a wading pool in Mississauga, Ontario, Canada, on July 4, 2020. Environment Canada issued on Saturday a heat warning for most of southern Ontario that is expected to stay in place until next week. (Photo by Zou Zheng/Xinhua)

Children play in a wading pool in Mississauga, Ontario, Canada, on July 4, 2020. Environment Canada issued on Saturday a heat warning for most of southern Ontario that is expected to stay in place until next week. (Photo by Zou Zheng/Xinhua)

Children play in a wading pool in Mississauga, Ontario, Canada, on July 4, 2020. Environment Canada issued on Saturday a heat warning for most of southern Ontario that is expected to stay in place until next week. (Photo by Zou Zheng/Xinhua)

Children play in a wading pool in Mississauga, Ontario, Canada, on July 4, 2020. Environment Canada issued on Saturday a heat warning for most of southern Ontario that is expected to stay in place until next week. (Photo by Zou Zheng/Xinhua)

Children play in a wading pool in Mississauga, Ontario, Canada, on July 4, 2020. Environment Canada issued on Saturday a heat warning for most of southern Ontario that is expected to stay in place until next week. (Photo by Zou Zheng/Xinhua)

A boy plays in a wading pool in Mississauga, Ontario, Canada, on July 4, 2020. Environment Canada issued on Saturday a heat warning for most of southern Ontario that is expected to stay in place until next week. (Photo by Zou Zheng/Xinhua)

A social distancing sign is seen beside a wading pool in Mississauga, Ontario, Canada, on July 4, 2020. Environment Canada issued on Saturday a heat warning for most of southern Ontario that is expected to stay in place until next week. (Photo by Zou Zheng/Xinhua)