With Tuesday and Wednesday expected to hit 32 and 34deg C respectively, people are being warned not to leave dogs inside vehicles "that can quickly become ovens".
Since November the city council has received 33 reports of dogs being left in hot cars. That compares with nine in the same period last year.
City council team leader animal management Mark Vincent said while most pet owners know leaving pets in hot cars can be fatal, some fail to realise just how quickly the effects of heatstroke can set in with tragic results.
On a 29 degree day, even with the windows open, the temperature inside a car can climb to 39 degrees in 10 minutes, and 48 degrees in 20 minutes, he said.
A dog can withstand a body temperature of 42 degrees for only a short time before suffering irreparable brain damage or even death, he said.
"If you have to leave your dog in the car you should check them every 10 minutes as a minimum to make sure they are okay," Mr Vincent said.
"If you don't have to take the dog with you in the car, then don't."
Animal Management Officers monitor dogs found in cars and will contact police and the SPCA if they are concerned about their welfare.
Mr Vincent said owners need to remember that shade and water are essential in the summer months, and he advises it's best to avoid taking dogs for a walk in the middle of the day when temperatures are highest.
Hot sand or asphalt surfaces can burn paws.
"Exercising your dog is great, first thing in the morning or later in the evening. But not at 2pm in the afternoon when it's really hot."
Signs of heat stroke in dogs include panting, red eye membranes, red mouth and looking dazed. Overheated dogs should be gradually cooled down, not put into cold water.
Tips for keeping your dog safe
1. Animals can quickly die in overheated vehicles.
2. Constant vehicle air circulation is essential for pets as temperatures soar.
3. Being able to cool down on wet towels will usually bring a lick of thanks from your pet.
4. Slow, progressive cooling is best for overheated dogs. Dunking dogs in cold water is not.
5. Avoid walking dogs on hot asphalt surfaces or beach dunes and wait for cooler temperatures later in the day.
- Star.kiwi