Health officers in B.C.'s Lower Mainland are warning people to be careful during a heat wave that has been forecast for the B.C. Day long weekend.

Environment Canada issued a special weather statement Friday morning, warning of hot and dry weather over 30 C throughout most of southern B.C.

Medical health officers with Vancouver Coastal Health issued a statement Friday, reminding residents and visitors to stay hydrated and to stay out of the sun for prolonged periods.

Vancouver Coastal Health also said that children and pets should never be left alone in parked cars.

The organization warned that when the outside temperate is 34 C, the temperature in a vehicle can reach 52 C within 20 minutes. It also said that leaving windows cracked open will not keep the inside temperature at a safe level.

The health authority also noted that fans are not effective in high-heat on their own, and suggests applying a cool water mist or a wet towel to one's body before sitting in front of a fan — or just seeking out air-conditioned facilities for relief.

The health authority is also asking residents to be good neighbours and check on the elderly and those who live alone to make sure they are coping.

The Vancouver Coastal Health Authority said symptoms of heat-related illness and heat exhaustion include thirst, dizziness, confusion, weakness and fainting. (CBC)

Symptoms of heat-related illness and heat exhaustion include thirst, dizziness, confusion, weakness and fainting.

Environment Canada forecast that temperatures could reach 32 C both Saturday and Sunday in inland sections of Metro Vancouver and the Fraser Valley, Howe Sound to Whistler, and the inland and east side regions of Vancouver Island.

Environment Canada is warning that temperatures in parts of the interior — including the Okanagan and Similkameen valleys; the Fraser Canyon; and the Nicola, South Thompson, Shuswap, and Boundary regions — could rise to the mid-30s on Saturday and upper-30s on Sunday.