Beagles can sleep outside on nice warm nights as long as you provide the beagle dog some shelter as in having the beagle dog a dog house where they can retreat too in the rain etc.
However if the weather is above 85 F then you should bring the beagle inside the house to sleep so it doesn't get too hot outside.
Or if the weather is cold outside then the beagle dog should also be brought inside to sleep because the dog could freeze to death as a result of the freezing weather.
But as long as the beagle dog is healthy and the weather is warm enough outside then the beagle dog can sleep outside.
Some beagle dogs can sleep outside without any problems while some beagle dogs may want to sleep inside and may bark if you leave them outside alone.
If the beagle dog barks at night then you should bring them inside but if not you can leave them outside if they want to be outside at night.