Today is the first day in the past 6 where there's a break in the record heat. The area I live in has experienced 4 new heat record setting days in the past week. Most of the houses in this area of Southern California were not built with air conditioning - mine included.
In the past 5 years I've learned that you want/need air conditioning perhaps a total of 5 or 6 days a year. The rest of the year the weather is either perfect or cool (you will use heat 5-6 months out of the year at night). With an average high temperature of 70 degrees and an average minimum temperature of 50 degrees - it's pretty much paradise year round.
When there is a heat wave people around here usually break out portable air conditioning units to keep their bedrooms comfortable for sleeping. I turn my air conditioner on perhaps 10 times a year total. It sort of looks like R2D2 and has a huge hose connected to a window vent. This year has been unseasonably hot due to a stalled moisture front which has taken the normally arid/dry air and made it humid and heavy - making it just miserable in the house (outside of my bedroom).
My cats don't like the portable air conditioner. For that matter neither do I; it's obnoxiously loud. After a while it's just oppressively noisy. Not unlike the wall unit in a cheap hotel.
My cats typically don't want to say in the cool room. Which means they end up in other areas of the house where the temperatures can reach over 100 degrees. Think about it like locking your cat or dog up inside a UPS delivery truck (the space) instead of your car. But not too much different.
My Maine Coon in his long, thick, black coat (designed for year round cold/freezing weather) is so hot that he pants constantly to keep cool. Seeing how uncomfortable he was and worrying about his health, I had a moment of clarity and I took the cooling packs I use for my muscles when I get sore from too much cycling - and I placed them on the cool tile counter top in my kitchen and I placed a thin hand-towel over them.
He immediately laid down and 5 minutes later he wasn't panting anymore. I discovered this 4 days ago and so I've kept a steady - freshly frozen set of cooling packs on the counter for him.
Another important thing you should do is make sure that your pets have plenty of water to drink. I will put ice cubes in their water to help cool it down - so they are drinking cool water.
The freezer packs under the towel is a certified hit. He spends most of the day on top of that cool little bed I've made for him and he's not panting anymore.
Remember, your pets are affected by the heat just as you are, but they don't always have the same options for cooling off - it's important to stay observant and have a couple of plans you can implement to cool them down should they start to show signs of heat related distress.