If you mean not inside a hen house?? since most chicks are hatched in spring or summer - not without a high mortality rate. Mom needs to occasionally come off the nest to eat , drink and poo. This would allow the eggs to cool too fast in cold climates. If she is directly outside and you can get to her and her eggs, I would set up a pen somewhere indoors for her. Give her food water and a cozy nest box to brood in and let her go for it. If she is too fiesty to pick up you can wait till its dark to make the move. Make sure your hands are ultra clean before handeling. Eggs are permeable and you dont need oils off your hands cloging the pores of the eggs. Any badly pooed on eggs toss. Dont forget to candle them- if she has been sitting on them for some time you will see veins forming and a dot floating= baby! If you dont see it at first wait a few days and recheck. GOOD LUCK!!