Concrete should be cured at a temperature between 50 and 90 degrees Fahrenheit. In an ideal world, the temperature of fresh concrete should be higher than 50 degrees Fahrenheit, but it should be cured and kept at 50 degrees Fahrenheit. Curing concrete at these temperatures will allow it to set properly. If the concrete is allowed to reach normal room temperature (60 degrees Fahrenheit), it will take longer to cure and may not set up hard enough. If this happens, you can bring the room temperature back up to 70 or 80 degrees, but never let it get below 50 degrees. The best way to cure concrete is with a moisture meter. This will tell you how much water is inside the concrete, which helps control the setting time and allows you to maintain the correct temperature. For example, if the meter reads that there is too much water in the concrete, then add more dry cement powder until it is just right. Too little water causes the concrete to set up too quickly; this can be corrected by adding more water when necessary. As soon as the concrete has set up enough that you cannot stir it, pour in more water until the next reading shows adequate moisture. You should also check the temperature every hour during initial curing and again before you wrap up the job. If necessary, raise or lower the oven rack to achieve the desired temperature.