Putting baby chicks outside.

My chicks are now 6 weeks old, whilst Ive been off work this last week and the weathers been nice I had them outside for the warmest parts of the day, they even slept in the shed last night for the first time.

However this afternoon whilst its not cold, it is rainning and despite a shelter the chicks seem to be stood out in the rain so Ive brought them back inside to be safe.

Is there a definative time that there ok outside? Theres so much contradictory info on the web that Im not sure what to do. If theres a safe temperature I could put them out on good days and keep them in on cold and wet days but is there a temperature I should be working to at this age?

Thanks

Indeed. The controlled enviroment of an incubator/brooder is all well and good but theres no subsitute for a broody!