My chicks started in a draft free shed in early April. I forget the actual outside temps., but at that time of year around here it's usually high 60s, low 70s during the day; 30s and 40s at night. We had an oil filled electric heater going in the shed, plus two heat lamps over their brooder.
By the end of the first week we realized it was getting too hot in the shed during the days since the shed was uninsulated and the afternoon sun was beating down on it. We moved them in their brooder with the draft guard and their two lamps to our screened porch.
At two weeks I started taking them outside for at least a few hours every day on windless days. The rest of the time they were in their brooder, surrounded by the draft guard and with both lights running.
By week three they were down to one light in the day, both lights at night - temps. in the high 70s during the day; lows in the 40s and 50s at night.
When they got to be 5 1/2 weeks old, my SO insisted I start leaving their light off at night. The nighttime temps. were in the high 50s, low 60s.
Never once did I see any distress from my chicks and believe me, I was constantly checking.
Now at almost a year old I have some very hardy chickens. They're outside no matter the weather. They have played in ice storms and don't mind heat.
I truly believe that getting them out off the heat as soon as your weather allows and letting them explore and be exposed to germs is good for them.
Just my 2 cents.
