Originally from Australia, cockatiels are used to living in varied temperatures in the wild. Pet cockatiels, on the other hand, rely on the creature comforts of climate control, and shouldn't be left outside in cold weather. If they are, their bodies can reach unsafe temperatures, and they may not survive.
Cockatiels naturally hail from Australia, where they can live in areas that reach relatively high and low temperatures. At its coldest, a cockatiel's natural habitat can reach approximately 40 degrees Fahrenheit. At its warmest, it may be over 109 degrees Fahrenheit. These are extremes, however, and subjecting a pet bird to either such temperature -- especially for an extended period of time -- can result in unsafe and unsustainable body temperatures.
A pet cockatiel should live in relatively consistent temperatures, as they are unable to adapt and regulate their body heat when environmental temperatures change. Ideally, a cockatiel's environment should be kept between 70 and 80 degrees Fahrenheit. While he can tolerate higher or lower temperatures, this is a comfortable medium for your bird that helps him maintain a healthy body temperature.
Your bird should live indoors, where you can control environmental factors that could make him uncomfortable. For example, your cockatiel shouldn't be exposed to direct sunlight or placed near fireplaces or space heaters, all of which can make him uncomfortably toasty. Similarly, air conditioner units, vents and drafty areas can give him a chill, making it critical that he stay indoors and away from cooler areas of the home.
Light and Dark
No matter the temperature, keeping your cockatiel inside ensures that he gets enough sleep. These birds need between 10 and 12 hours of uninterrupted sleep every night, and if your bird is outside or in an area exposed to natural light, it may get in the way of his beauty sleep. At night, keep his cage in a room with shades and curtains, or cover his cage while he sleeps. It helps him get the rest he needs so he stays healthy and friendly.