Can you put parakeets outside for awhile in warm weather?

This depends on a couple of factors, but generally the answer is "yes".

1. What is meant by "parakeet"? The term "parakeet" is a generalised term to cover numerous species of smaller, long-tailed parrots. 'Parakeet' also tends to be a commonly mistaken name for budgerigars, small members of the parrot species. Birds classified under the term parakeet include budgies, cockatiels, rosellas and lorikeets. Different birds have different levels of hardiness. Budgies, for example, are not very hardy in draughts.

2. What is meant by "warm weather"? Australia's definition of warm weather is vastly different to that of England, for instance. In Australia, "warm" is anything over 26 degrees Celsius whilst in England that is a heatwave. English folk might consider 16 degrees to be warm, but that would be too cold for a parrot of any sort to be outside. They are essentially warm to hot weather birds.