Generally speaking, hot weather precautions should be taken whenever the temperature reaches 85 degrees F. or more. Needed preparations include: casting floor slabs after the structure has been roofed; having extra help on hand during hot weather; specifying a water-reducing retarder in the concrete mix; not using dark colors when painting metal surfaces that may be later used to hold or transport concrete; and being ready at the job site when the ready mix truck arrives. As for procedures, try to confine all concreting operations to the evening and night. Don't cast concrete in direct sunlight without providing a sunshade and a windbreak. Shield test specimens from sun, heat, and wind. And remember, protection and curing are especially important during hot weather. Don't interrupt the continuity of curing. Use continuous water curing, if possible; if this is not practicable, use an effective opaque water barrier.