My mixed flock of four week olds , were turned out into their outside pens the day before yesterday ,> They've had two wonderful days in the sunshine (with access to shade of course ) with temps of 25C . Today though the temp has dropped to 15c with rain forcast all day . Should I bring them back in under the lamp or leave them to toughen up ? They are in a dry place with the run out in the weather ! ????