It's supposed to be 95 for first week, then decrease by 5 degrees every week until they are feathered out. Usually about 6 weeks but some may be a bit longer. Keep a thermometer in the brooder to monitor temps closely.
If it's cold in your area, you may still want to keep a heat lamp on them during the coldest times after they've feathered out. You can tell if it's still too cold if they stay huddled up under the heat directly instead of spreading out.
In all cases make sure they do have an area where they can move out of the direct heat to prevent overheating. They need ventilation but should not be in drafty areas.
I agree with the people that say 95. Watch them after that- they will let you know if they are too hot or too cold. If they spread out and hug the ground and pant they are too hot, if they are huddled together under the light they are too cold. If they wander around doing chick things they are just right.